feat!: remove extraneous thrown exception for Java major version bump

[miraleung]

Removes an unnecessary exception thrown from the ServiceSettings and ServiceStubSettings overrides of gax-java’s StubSettings.applyToAllUnaryMethods method, which does not throw an exception. This was a legacy artifact from the monolith generator, and we can finally remove it with the upcoming client library major version bump.

This branch will not be merged into main until all stakeholders are ready for the major version update.

Example of affected client library classes:

• See the golden files in this PR
• AutoscalingPolicyServiceStubSettings.java
• AutoscalingPolicyServiceSettings.java

cc @chingor13

[codecov]

Codecov Report

Merging #784 (36b46c2) into main/java_major_version_bump (9432979) will decrease coverage by 0.00%.
The diff coverage is n/a.

@@                       Coverage Diff                        @@
##           main/java_major_version_bump     #784      +/-   ##
================================================================
- Coverage                         91.27%   91.27%   -0.01%     
================================================================
  Files                               140      140              
  Lines                             14952    14948       -4     
  Branches                           1074     1074              
================================================================
- Hits                              13648    13644       -4     
  Misses                             1011     1011              
  Partials                            293      293              

Impacted Files	Coverage Δ
...apic/composer/comment/SettingsCommentComposer.java	94.02% <ø> (-0.09%)	⬇️
...r/common/AbstractServiceSettingsClassComposer.java	97.85% <ø> (-0.01%)	⬇️
...mmon/AbstractServiceStubSettingsClassComposer.java	97.16% <ø> (-0.01%)	⬇️

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