Dotty

Remove unnecessary uses of uncheckedNN #35911

Job	Run time
test	31m 49s
MiMa	11m 15s
test_sbt	19m 39s
community_build_b	1h 30m 53s
test_non_bootstrapped	0s
test_windows_fast	36m 34s
build-msi-package	0s
community_build_a	48m 56s
community_build_c	58m 26s
test_windows_full	0s
test_scala2_library_tasty	0s
test_java8	0s
build-sdk-package / build	8m 56s
test-msi-package	0s
build-chocolatey-package / build	24s
test-chocolatey-package	0s
publish_release	0s
publish_nightly	0s
nightly_documentation	0s
open_issue_on_failure	0s
	5h 6m 52s

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