ci/gnuassertrr: Assertion `node->header != gc_bigval_sentinel_tag' failed

[inkydragon]

Assertion failed occurs on some pr's that only modify documentation and tests.

• Tests for two AbstractString methods #56247
  Failed x2: https://buildkite.com/julialang/julia-master/builds/43122#0193da38-73f4-41a6-9fe5-6822c8044d7d/866-1289

      From worker 13:	julia: /cache/build/tester-demeter6-11/julialang/julia-master/src/gc-stock.h:492: gc_big_object_link: Assertion `node->header != gc_bigval_sentinel_tag' failed.
      From worker 13:
      From worker 13:	[3285] signal 6 (-6): Aborted
      From worker 13:	in expression starting at none:1
...
compileall                                       (13) |         failed at 2024-12-18T15:02:41.182
Test Failed at /cache/build/tester-demeter6-11/julialang/julia-master/julia-bbaa6059fd/share/julia/test/compileall.jl:6
  Expression: success(pipeline(`$(Base.julia_cmd()) --compile=all --strip-ir --output-o $(dir)/sys.o.a -e 'exit()'`, stderr = stderr))

• docs: fix edge case in rational number conversion float(a//b) #56772
  Failed x1: https://buildkite.com/julialang/julia-master/builds/43129#0193da31-fea7-480b-a143-33ea4b067987/866-1291
• docs: fix scope type of a struct to hard #56755
  Failed x2: https://buildkite.com/julialang/julia-master/builds/43130#0193dc61-12fa-49e1-8cfd-cf4b76704853/866-1301

[vtjnash]

Also seen here: https://buildkite.com/julialang/julia-master/builds/43185#0193e594-4b30-4037-adca-5143b10f6c93, so probably a missing gc root in the ircode.c file