[ci] fix shellcheck warnings in CI scripts #9206

Job	Run time
r-package (clang16, R-devel)	11m 22s
r-sanitizers (ubuntu-latest, R-devel, gcc ASAN/UBSAN)	15m 3s
r-package (clang17, R-devel)	11m 48s
r-sanitizers (ubuntu-latest, R-devel, clang ASAN/UBSAN)	29m 23s
r-package (clang18, R-devel)	11m 45s
r-package (ubuntu-latest, gcc, R 3.6, cmake)	8m 25s
r-package (clang19, R-devel)	12m 19s
r-package (ubuntu-latest, gcc, R 4.3, cmake)	9m 27s
r-package (gcc14, R-devel)	10m 41s
r-package (ubuntu-latest, clang, R 4.3, cmake)	10m 19s
r-package (intel, R-devel)	10m 59s
r-package (macos-13, gcc, R 4.3, cmake)	18m 31s
r-package (macos-13, clang, R 4.3, cmake)	16m 53s
r-package (windows-latest, MINGW, R 3.6, cmake)	11m 32s
r-package (windows-latest, MINGW, R 4.3, cmake)	17m 42s
r-package (windows-2019, MSVC, R 3.6, cmake)	22m 35s
r-package (windows-2022, MSVC, R 4.3, cmake)	29m 17s
r-package (windows-latest, MINGW, R 3.6, cran)	14m 46s
r-package (windows-latest, MINGW, R 4.3, cran)	15m 41s
r-package (ubuntu-latest, gcc, R 4.3, cran)	10m 42s
r-package (macos-13, clang, R 4.3, cran)	16m 50s
r-package (macos-14, clang, R 4.3, cran)	7m 9s
all-r-package-jobs-successful	2s
	5h 23m 11s

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