GH-49898: [C++][CI] Use mold in more builds

[pitrou]

Rationale for this change

We're currently using the mold linker only on a couple of C++ builds. This PR uses it in more builds to get faster link times and thus faster CI builds.

Are these changes tested?

Yes, by CI builds.

Are there any user-facing changes?

No.

• GitHub Issue: [C++][CI] Use mold in more builds #49898

[pitrou]

@github-actions crossbow submit -g cpp

[github-actions]

Revision: eb0c13a

Submitted crossbow builds: ursacomputing/crossbow @ actions-4c03283919

Task	Status
example-cpp-minimal-build-static
example-cpp-minimal-build-static-system-dependency
example-cpp-tutorial
test-build-cpp-fuzz
test-conda-cpp
test-conda-cpp-valgrind
test-debian-13-cpp-amd64
test-debian-13-cpp-i386
test-debian-experimental-cpp-gcc-15
test-fedora-42-cpp
test-ubuntu-22.04-cpp
test-ubuntu-22.04-cpp-bundled
test-ubuntu-22.04-cpp-emscripten
test-ubuntu-22.04-cpp-no-threading
test-ubuntu-24.04-cpp
test-ubuntu-24.04-cpp-bundled-offline
test-ubuntu-24.04-cpp-gcc-13-bundled
test-ubuntu-24.04-cpp-gcc-14
test-ubuntu-24.04-cpp-minimal-with-formats
test-ubuntu-24.04-cpp-thread-sanitizer

[pitrou]

@kou Could you take a look at this PR?

[kou]

+1

[conbench-apache-arrow]

After merging your PR, Conbench analyzed the 0 benchmarking runs that have been run so far on merge-commit 684c21e.

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