[clang] [NFC][analyzer] Simplify ownership of checker objects (PR #128887)

[Donát Nagy via cfe-commits]

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@@ -41,8 +42,8 @@ CheckerManager::CheckerManager(AnalyzerOptions &AOptions,
 }
 
 CheckerManager::~CheckerManager() {
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NagyDonat wrote:

Good suggestion, I didn't know that `= default` works with out-of-line declarations.

https://github.com/llvm/llvm-project/pull/128887