Add lock on _checkRegistry operations

[YuliiaKovalova]

Fixes #11319

Context

It looks like the environment modifies _checkRegistry concurrently due to throttling logic

msbuild/src/Build/BuildCheck/Infrastructure/BuildCheckManagerProvider.cs

Line 373 in 4042363

foreach (var throttledCheck in _checkRegistry.FindAll(c => c.MaterializedCheck?.IsThrottled ?? false))

and

msbuild/src/Build/BuildCheck/Infrastructure/BuildCheckManagerProvider.cs

Line 380 in 4042363

private void RemoveCheck(CheckFactoryContext checkToRemove)

In RemoveChecksAfterExecutedActions the code is processing throttled checks and RemoveCheck method is modifying the _checkRegistry while the FindAll loop is still iterating over it.

Changes Made

add lock for the _checkRegistry operations to avoid issues with synchronization.