[clang-tools-extra] [clang-tidy] Move part of bugprone-unhandled-code-paths to a new check readability-trivial-switch (PR #198237)

[LLVM Continuous Integration via cfe-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-ppc64le-linux-test-suite` running on `ppc64le-clang-test-suite` while building `clang-tools-extra` at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/95/builds/21447

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

```
Step 6 (test-build-unified-tree-check-all) failure: 1200 seconds without output running [b'ninja', b'check-all'], attempting to kill
...
PASS: LLVM :: CodeGen/AMDGPU/directive-amdgcn-target.ll (112116 of 112126)
PASS: LLVM :: tools/llvm-objcopy/ELF/cross-arch-headers.test (112117 of 112126)
PASS: LLVM :: CodeGen/AMDGPU/elf-header-flags-mach.ll (112118 of 112126)
PASS: Clang :: Driver/x86-target-features.c (112119 of 112126)
PASS: Clang :: Driver/arm-cortex-cpus-1.c (112120 of 112126)
PASS: LLVM :: tools/llvm-readobj/ELF/AMDGPU/elf-headers.test (112121 of 112126)
PASS: Clang :: Driver/arm-cortex-cpus-2.c (112122 of 112126)
PASS: ScudoStandalone-Unit :: ./ScudoUnitTest-powerpc64le-Test/101/387 (112123 of 112126)
PASS: ScudoStandalone-Unit :: ./ScudoCxxUnitTest-powerpc64le-Test/0/3 (112124 of 112126)
PASS: ScudoStandalone-Unit :: ./ScudoUnitTest-powerpc64le-Test/110/387 (112125 of 112126)
command timed out: 1200 seconds without output running [b'ninja', b'check-all'], attempting to kill
process killed by signal 9
program finished with exit code -1
elapsedTime=9712.483735

```

</details>

https://github.com/llvm/llvm-project/pull/198237