chore: normalize "lib" vs "pkg" terminology in tests

[jbedard]

Changes are visible to end-users: no

Test plan

• Covered by existing test cases

[aspect-workflows]

Test

8 test targets passed

Targets

//examples/deps_pkg_transpiler/b:b_typecheck_test [k8-fastbuild]                53ms
//examples/deps_pkg_transpiler:importer_linked_ts_typecheck_test [k8-fastbuild] 33ms
//examples/deps_pkg_transpiler:importer_rel_ts_typecheck_test [k8-fastbuild]    32ms
//examples/deps_pkg_transpiler:lib_typecheck_test [k8-fastbuild]                27ms
//examples/dts_pkg:importer_linked_test [k8-fastbuild]                          100ms
//examples/dts_pkg:importer_rel_test [k8-fastbuild]                             66ms
//examples/simple:test_dts [k8-fastbuild]                                       143ms
//examples/simple:test_js [k8-fastbuild]                                        92ms

Total test execution time was 546ms. 77 tests (90.6%) were fully cached saving 11s.

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