fix: require component for user APIs

[wolfkill]

Fixes #14594.

Summary

• mark the user API component query parameter as required for get/delete/update endpoints
• reject missing component values with a clear bad request instead of constructing null user names or surfacing an NPE
• normalize validated component values before update/delete user lookups

Tests

• JAVA_HOME=/opt/homebrew/opt/openjdk@21/libexec/openjdk.jdk/Contents/Home ./mvnw -pl pinot-controller -am -Dtest=PinotAccessControlUserRestletResourceTest#testGetUserWithoutComponentReturnsClearBadRequest+testUserComponentQueryParamIsRequiredInSwagger -DfailIfNoTests=false -Dsurefire.failIfNoSpecifiedTests=false test
• JAVA_HOME=/opt/homebrew/opt/openjdk@21/libexec/openjdk.jdk/Contents/Home ./mvnw -pl pinot-controller -am -Dtest=PinotAccessControlUserRestletResourceTest -DfailIfNoTests=false -Dsurefire.failIfNoSpecifiedTests=false test
• git diff --check

[codecov-commenter]

Codecov Report

❌ Patch coverage is 92.30769% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 64.38%. Comparing base (9f8eb1a) to head (6517e60).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
...sources/PinotAccessControlUserRestletResource.java	92.30%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #18606      +/-   ##
============================================
+ Coverage     64.37%   64.38%   +0.01%     
  Complexity     1137     1137              
============================================
  Files          3335     3335              
  Lines        206065   206073       +8     
  Branches      32136    32137       +1     
============================================
+ Hits         132649   132676      +27     
+ Misses        62760    62750      -10     
+ Partials      10656    10647       -9     

Flag	Coverage Δ
custom-integration1	100.00% <ø> (ø)
integration	100.00% <ø> (ø)
integration1	100.00% <ø> (ø)
integration2	0.00% <ø> (ø)
java-21	64.38% <92.30%> (+0.01%)	⬆️
temurin	64.38% <92.30%> (+0.01%)	⬆️
unittests	64.38% <92.30%> (+0.01%)	⬆️
unittests1	56.79% <ø> (+0.02%)	⬆️
unittests2	36.92% <92.30%> (-0.02%)	⬇️

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