Disable errorprone RequestExplicitNullMarking

[trask]

Currently not causing failures, but spamming:

C:\src\opentelemetry-java\context\src\main\java\io\opentelemetry\context\propagation\internal\ExtendedTextMapGetter.java:17: Note: [RequireExplicitNullMarking] Top-level classes must either be directly annotated with @NullMarked/@NullUnmarked or be in a package or module that is explicitly @NullMarked/@NullUnmarked.
public interface ExtendedTextMapGetter<C> extends TextMapGetter<C> {
       ^
    (see https://errorprone.info/bugpattern/RequireExplicitNullMarking)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.08%. Comparing base (60698f7) to head (cf71fa5).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##               main    #7890   +/-   ##
=========================================
  Coverage     90.08%   90.08%           
  Complexity     7325     7325           
=========================================
  Files           825      825           
  Lines         22051    22051           
  Branches       2179     2179           
=========================================
  Hits          19865    19865           
  Misses         1506     1506           
  Partials        680      680           

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