ZeroJank: Make version-gate flag non-static

The flag used for version-gating zerojankProxy should really be
non-static so compatChanges check is true to app's targetSdk introduced
in [1]

[1]: I6b8787a2ada0b4a60e6b448b674d05e172e594a7

Bug: 349701662
Bug: 352594277
Test: atest CtsInputMethodTestCases
Flag: compatchange_for_zerojankproxy

Change-Id: I5b429d9405984728b57f8665ca486ff4132ac837