refactor: make root workspace bzlmod only

[gregmagolan]

Reduce the maintenance burden caused by duplication of Bazel deps in the root workspace.

CI coverage for WORKSPACE is still in-place in all the e2e workspaces.

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Changes are visible to end-users: no

Test plan

• Covered by existing test cases

[aspect-workflows]

Test

12 test targets passed

Targets

//:bazel_version_test [k8-fastbuild]                                         243ms
//lib/tests/bats:args [k8-fastbuild]                                         3s
//lib/tests/bats:basic [k8-fastbuild]                                        3s
//lib/tests/bats:env [k8-fastbuild]                                          3s
//lib/tests/bats:env_expansion [k8-fastbuild]                                3s
//lib/tests/copy_to_directory:case_22_test [k8-fastbuild]                    459ms
//lib/tests/copy_to_directory_bin_action:test [k8-fastbuild]                 445ms
//lib/tests/jq:check_stamped [k8-fastbuild]                                  256ms
//lib/tests/yq:check_stamped [k8-fastbuild]                                  172ms
//shlib/tests/lib_tests/assertions_tests:assert_equal_test [k8-fastbuild]    322ms
//shlib/tests/lib_tests/assertions_tests:assert_match_test [k8-fastbuild]    420ms
//shlib/tests/lib_tests/assertions_tests:assert_no_match_test [k8-fastbuild] 629ms

Total test execution time was 15s. 209 tests (94.6%) were fully cached saving 45s.

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Test

e2e/copy_action

All tests were cache hits

1 test (100.0%) was fully cached saving 59ms.

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Test

e2e/copy_to_directory

All tests were cache hits

6 tests (100.0%) were fully cached saving 750ms.

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Test

e2e/coreutils

All tests were cache hits

4 tests (100.0%) were fully cached saving 742ms.

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Test

e2e/external_copy_to_directory

All tests were cache hits

1 test (100.0%) was fully cached saving 59ms.

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Test

e2e/smoke

All tests were cache hits

6 tests (100.0%) were fully cached saving 1s.

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Buildifier      Format      Gazelle