Add unset values in TestFillConfigWithFlagsValidVals #10273

Job	Run time
addlicense	16s
build	1m 16s
lint	1m 6s
test (macos)	4m 49s
test (windows)	6m 42s
python-format	6s
python-lint	6s
test (ubuntu)	3m 54s
test-race	5m 18s
test-sgcollect (macos-latest)	33s
test-sgcollect (windows-latest)	3m 48s
test-stats-definition-exporter (macos-latest)	3m 24s
test-sgcollect (ubuntu-latest)	27s
test-stats-definition-exporter (windows-latest)	3m 53s
test-stats-definition-exporter (ubuntu-latest)	1m 18s
	36m 56s

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