Fix building fresh (non-incremental) sysimages on Julia nightly (Julia 1.12)

[KristofferC]

Fixes #989.

Replaces #996 (closes #996).

[codecov]

Codecov Report

Attention: Patch coverage is 28.57143% with 5 lines in your changes missing coverage. Please review.

Project coverage is 84.07%. Comparing base (38629b0) to head (b719aaf).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
src/PackageCompiler.jl	28.57%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1002      +/-   ##
==========================================
- Coverage   84.56%   84.07%   -0.50%     
==========================================
  Files           3        3              
  Lines         823      829       +6     
==========================================
+ Hits          696      697       +1     
- Misses        127      132       +5     

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[DilumAluthge]

Closes #996, I'm guessing?

[DilumAluthge]

Looks like we are now hitting:

error during bootstrap:

LoadError(at "/opt/hostedtoolcache/julia/nightly/x64/share/julia/base/Base_compiler.jl" line 291: ErrorException("File "./../usr/share/julia/Compiler/src/Compiler.jl" not found"))

[KristofferC]

Requires JuliaLang/julia#56601

[DilumAluthge]

It looks like nightly CI might timeout here, in which case we will need to increase the timeouts along the lines of #1003.

[DilumAluthge]

Indeed, nightly CI timed out at the old timeout (90 minutes) on this PR. Let's see if increasing the timeouts (#1003) fixes things.

[DilumAluthge]

CI is all green.

Codecov is unhappy, but that's just because we don't run code coverage on every job in our matrix (to try to save some CI time).

[DilumAluthge]

@KristofferC Is this good to merge?