[llvm] [MemProf] Streamline and avoid unnecessary context id duplication (PR #107918)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clangd-ubuntu-tsan` running on `clangd-ubuntu-clang` while building `llvm` at step 6 "test-build-clangd-clangd-index-server-clangd-indexer-check-clangd".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/134/builds/5014

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 6 (test-build-clangd-clangd-index-server-clangd-indexer-check-clangd) failure: test (failure)
******************** TEST 'Clangd :: utf8.test' FAILED ********************
Exit Code: 66

Command Output (stderr):
--
RUN: at line 1: clangd -lit-test < /vol/worker/clangd-ubuntu-clang/clangd-ubuntu-tsan/llvm-project/clang-tools-extra/clangd/test/utf8.test | /vol/worker/clangd-ubuntu-clang/clangd-ubuntu-tsan/build/bin/FileCheck -strict-whitespace /vol/worker/clangd-ubuntu-clang/clangd-ubuntu-tsan/llvm-project/clang-tools-extra/clangd/test/utf8.test
+ clangd -lit-test
+ /vol/worker/clangd-ubuntu-clang/clangd-ubuntu-tsan/build/bin/FileCheck -strict-whitespace /vol/worker/clangd-ubuntu-clang/clangd-ubuntu-tsan/llvm-project/clang-tools-extra/clangd/test/utf8.test
WARNING: ThreadSanitizer: unexpected memory mapping 0x79ffff072000-0x79ffff500000
FATAL: ThreadSanitizer: unexpectedly found incompatible memory layout.
FATAL: Please file a bug.
I[17:22:46.171] clangd version 20.0.0git (https://github.com/llvm/llvm-project.git 524a028f69cdf25503912c396ebda7ebf0065ed2)
I[17:22:46.171] Features: linux+debug+tsan+grpc
I[17:22:46.171] PID: 84610
I[17:22:46.171] Working directory: /vol/worker/clangd-ubuntu-clang/clangd-ubuntu-tsan/build/tools/clang/tools/extra/clangd/test
I[17:22:46.171] argv[0]: clangd
I[17:22:46.171] argv[1]: -lit-test
I[17:22:46.171] Starting LSP over stdin/stdout
V[17:22:46.171] <<< {
  "id": 0,
  "jsonrpc": "2.0",
  "method": "initialize",
  "params": {
    "capabilities": {
      "offsetEncoding": [
        "utf-8",
        "utf-16"
      ]
    },
    "processId": 123,
    "rootPath": "clangd",
    "trace": "off"
  }
}

I[17:22:46.171] <-- initialize(0)
I[17:22:46.173] --> reply:initialize(0) 1 ms
==================
WARNING: ThreadSanitizer: signal-unsafe call inside of a signal (pid=84610)
    #0 free <null> (clangd+0xd37eaf) (BuildId: 8c0d4391a55323945b9df670c6f4c15bddec5b8a)
    #1 __call_tls_dtors <null> (libc.so.6+0x438b3) (BuildId: f7307432a8b162377e77a182b6cc2e53d771ec4b)
    #2 SignalHandler(int) /vol/worker/clangd-ubuntu-clang/clangd-ubuntu-tsan/llvm-project/llvm/lib/Support/Unix/Signals.inc (clangd+0xf63c8f) (BuildId: 8c0d4391a55323945b9df670c6f4c15bddec5b8a)
    #3 __tsan::CallUserSignalHandler(__tsan::ThreadState*, bool, bool, int, __sanitizer::__sanitizer_siginfo*, void*) tsan_interceptors_posix.cpp.o (clangd+0xd40d65) (BuildId: 8c0d4391a55323945b9df670c6f4c15bddec5b8a)
    #4 llvm::raw_fd_ostream::write_impl(char const*, unsigned long) /vol/worker/clangd-ubuntu-clang/clangd-ubuntu-tsan/llvm-project/llvm/lib/Support/raw_ostream.cpp:766:19 (clangd+0xf49e92) (BuildId: 8c0d4391a55323945b9df670c6f4c15bddec5b8a)
    #5 llvm::raw_ostream::flush_nonempty() /vol/worker/clangd-ubuntu-clang/clangd-ubuntu-tsan/llvm-project/llvm/lib/Support/raw_ostream.cpp:224:3 (clangd+0xf4838b) (BuildId: 8c0d4391a55323945b9df670c6f4c15bddec5b8a)
    #6 flush /vol/worker/clangd-ubuntu-clang/clangd-ubuntu-tsan/llvm-project/llvm/include/llvm/Support/raw_ostream.h:200:7 (clangd+0x2eba3f4) (BuildId: 8c0d4391a55323945b9df670c6f4c15bddec5b8a)
    #7 clang::clangd::(anonymous namespace)::JSONTransport::sendMessage(llvm::json::Value) /vol/worker/clangd-ubuntu-clang/clangd-ubuntu-tsan/llvm-project/clang-tools-extra/clangd/JSONTransport.cpp:141:9 (clangd+0x2eba3f4)
    #8 clang::clangd::(anonymous namespace)::JSONTransport::reply(llvm::json::Value, llvm::Expected<llvm::json::Value>) /vol/worker/clangd-ubuntu-clang/clangd-ubuntu-tsan/llvm-project/clang-tools-extra/clangd/JSONTransport.cpp:89:7 (clangd+0x2eb71c3) (BuildId: 8c0d4391a55323945b9df670c6f4c15bddec5b8a)
    #9 clang::clangd::ClangdLSPServer::MessageHandler::ReplyOnce::operator()(llvm::Expected<llvm::json::Value>) /vol/worker/clangd-ubuntu-clang/clangd-ubuntu-tsan/llvm-project/clang-tools-extra/clangd/ClangdLSPServer.cpp:381:24 (clangd+0x2c75c1a) (BuildId: 8c0d4391a55323945b9df670c6f4c15bddec5b8a)
    #10 void llvm::detail::UniqueFunctionBase<void, llvm::Expected<llvm::json::Value>>::CallImpl<clang::clangd::ClangdLSPServer::MessageHandler::ReplyOnce>(void*, llvm::Expected<llvm::json::Value>&) /vol/worker/clangd-ubuntu-clang/clangd-ubuntu-tsan/llvm-project/llvm/include/llvm/ADT/FunctionExtras.h:222:12 (clangd+0x2c76cb0) (BuildId: 8c0d4391a55323945b9df670c6f4c15bddec5b8a)
...

```

</details>

https://github.com/llvm/llvm-project/pull/107918