Fix ccache restore key for check-macos-12-cmake-clang

[tautschnig]

We must not pick up a cache generated by the non-Glucose job, which has the same prefix. Doing so would result in a cache that mixes different configurations, and ccache may end up pruning the wrong ones.

While at it, also insert hyphens to make cache entry names easier to read.

Performance note: in #7428, check-macos-12-cmake-clang just spent 28 minutes building with 0 cache hits, despite 1115 entries in the cache. Other jobs completed the build stage within seconds. I have manually removed the possibly offending caches from https://github.com/diffblue/cbmc/actions/caches, but we may need to do another cleanup once this PR is merged.

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[codecov]

Codecov Report

Base: 78.50% // Head: 78.49% // Decreases project coverage by -0.02% ⚠️

Coverage data is based on head (358386e) compared to base (3f578e1).
Patch has no changes to coverable lines.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #7522      +/-   ##
===========================================
- Coverage    78.50%   78.49%   -0.02%     
===========================================
  Files         1663     1663              
  Lines       191297   191331      +34     
===========================================
+ Hits        150174   150180       +6     
- Misses       41123    41151      +28     

Impacted Files	Coverage Δ
src/solvers/smt2/smt2_dec.cpp	70.16% <0.00%> (-3.12%)	⬇️
src/goto-checker/solver_factory.cpp	81.23% <0.00%> (-0.79%)	⬇️
src/solvers/smt2/smt2_conv.cpp	67.26% <0.00%> (-0.38%)	⬇️
src/solvers/smt2/smt2_conv.h	87.50% <0.00%> (ø)

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