Reject transformations on SubDataFrame with copycols=false #2774

Job	Run time
Julia 1 - ubuntu-latest - x64 - pull_request	42m 38s
Documentation	7m 5s
Julia 1 - macos-latest - aarch64 - pull_request	34m 29s
Julia 1.10 - ubuntu-latest - x64 - pull_request	32m 42s
Julia nightly - ubuntu-latest - x64 - pull_request	39m 27s
Julia 1 - windows-latest - x86 - pull_request	1h 27m 37s
	4h 3m 58s

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