Enable more errorprone checks

[findepi]

The checks are defined here: https://github.com/prestosql/presto/blob/fcb91631a655f8af7c6aeb803861d1c738f67281/pom.xml#L1424

Here's how to run the checks: https://github.com/prestosql/presto/blob/fcb91631a655f8af7c6aeb803861d1c738f67281/.github/workflows/ci.yml#L72-L73

• Enable on error level:
  • [x] EqualsIncompatibleType (https://github.com/prestosql/presto/pull/4181)
  • [x] NullOptional
  • [x] BadInstanceof
  • [x] BoxedPrimitiveConstructor (https://github.com/prestosql/presto/pull/4269)
  • [x] CompareToZero
  • [x] OptionalEquality (https://github.com/trinodb/trino/pull/6562)
  • [x] UnusedVariable (https://github.com/prestosql/presto/pull/5642)
  • [x] InconsistentHashCode
  • [ ] ImmutableEnumChecker, ImmutableAnnotationChecker (https://github.com/prestosql/presto/pull/4470)
  • [x] ObjectToString
  • [ ] UnnecessaryParentheses
  • [ ] Enable MissingCasesInEnumSwitch errorprone check #6764
  • [ ] DefaultCharset (warning: this one is tricky)
  • ...
• [ ] Enable format checks on loggers (https://github.com/prestosql/presto/issues/4189)
• [ ] Enable errorprone's default checks (remove -XepDisableAllChecks)
  • hint: this may require multiple changes in the source code to address multiple checks, so it's good idea to do this step by step in multiple PRs.
• ... -- we may propose some other checks that errorprone does not run on error level by default, see http://errorprone.info/bugpatterns#on-by-default--warning

[chhsiao90]

BadInstanceof, CompareToZero, InconsistentHashCode, ObjectToString are enabled in #4289

[chhsiao90]

ImmutableEnumChecker, ImmutableAnnotationChecker, Immutable, ImmutableModification were enabled in #4470

[findepi]

I added OptionalEquality to the list. It's apparently possible to make a mistake when refactoring the code, like here https://github.com/prestosql/presto/blob/ece62ab29bc96a723669687e17bc2eef183a2d4d/presto-base-jdbc/src/main/java/io/prestosql/plugin/jdbc/JdbcTypeHandle.java#L130