Remove the fast path in art_quick_resolve_string.

The stub is now only being used in very rare cases. A follow-up
change will remove the string dex cache from java.lang.Class.

0% performance regression on x86/x64/arm/arm64
Some performance regression expected on mips (which always calls
the stub).

Test: test-art-host test-art-target

Change-Id: I1f410924ef2f7d82eb3b39b4d52c283825306d2a