Revert recent JIT code cache changes

Flakiness observed on the bots.

Revert "Jit Code Cache instruction pipeline flushing"
This reverts commit 56fe32ee.

Revert "ARM64: More JIT Code Cache maintenace"
This reverts commit 17272ab6.

Revert "ARM64: JIT Code Cache maintenance"
This reverts commit 3ecac070.

Revert "Change flush order in JIT code cache"
This reverts commit 43ce5f82.

Revert "Separate rw from rx views of jit code cache"
This reverts commit d1dbb74e.

Test: art/test.py --target --64
Bug: 64527643
Bug: 62356545
Change-Id: Ifa10ac77a60ee96e8cb68881bade4d6b4f828714