[Manual] Fix local variable names

* Run "Local variable naming convention" inspection in Intellij
* Fix warnings through automatic refactoring
* Move certain constant local variables out as a "private static final"
  variable at class level

Bug: 63597465
Test: make checkbuild, no functional changes
Change-Id: Ifa97e8c8dc2c76a4456d26d5f53294efcb9955ac