v1.40.1-sym1-newgc10: Merge remote-tracking branch 'sym/sym-1.40.x' into newgc

Conflicts:
	.github/actions/4d-test-libs/action.yml
	.github/actions/6-integration-test/action.yml

v1.40.0-sym1-newgc10

Update AA handling to avoid faketypeinfo and associated segfaults

v1.40.0-sym1-newgc9

fix race for scanning just-starting threads

v1.40.0-sym1-newgc8

Bump SDC to fix fiber issue

v1.40.0-sym1-newgc7

Add quiet option for sdc gc to avoid tripping up CI

v1.40.0-sym1-newgc6

Bump to latest SDC, including all hang fixes. Fix memory leak.

v1.40.0-sym1-newgc5

Add option to set number of threads that parallel scan.

v1.40.0-sym1-newgc4: druntime: Enable DRT_* environment variables support by default

In order to trivially switch between GCs.

v1.40.0-sym1-newgc3

Bump SDC

v1.40.0-sym1-newgc2

Bump SDC