Reland "arm64/nterp: Load the next instruction before call."

This reverts commit ede1275a1e6ecaff9a3ab170fe7098f1d50e0811.

Reason for revert: Fixed string-init to preserve vreg number
instead of `this` as the latter may be stale for moving GC.

Test: testrunner.py --target --64 --interpreter
Test: testrunner.py --target --64 --interpreter --gcstress
Flag: EXEMPT PURE_REFACTOR
Bug: 480444811
Change-Id: Ica2ffecbb6e6aea5e2ae40c5abc691d3a765bcba