ScannerTokens: keep multiple outdents to swap `,` #4372

Job	Run time
testLatestScala (JVM, 2.12.19, 8)	3m 28s
Scalafmt	28s
++2.13.13 download-scala-library testsJVM/slow:test	3m 31s
testLatestScala (JVM, 2.12.19, 21)	3m 6s
testOlderScalaOnJVM (2.11.12)	4m 5s
communitytest/test	4m 9s
testLatestScala (JVM, 2.13.13, 8)	3m 8s
mima	5m 53s
testOlderScalaOnJVM (2.12.16)	3m 17s
testLatestScala (JVM, 2.13.13, 21)	3m 10s
Windows tests	3m 51s
testOlderScalaOnJVM (2.12.17)	3m 10s
testLatestScala (JS, 2.12.19, 8)	3m 42s
testOlderScalaOnJVM (2.12.18)	2m 57s
testLatestScala (JS, 2.12.19, 21)	3m 41s
testOlderScalaOnJVM (2.13.10)	3m 15s
testLatestScala (JS, 2.13.13, 8)	3m 42s
testOlderScalaOnJVM (2.13.11)	3m 14s
testLatestScala (JS, 2.13.13, 21)	3m 51s
testOlderScalaOnJVM (2.13.12)	3m 17s
testLatestScala (Native, 2.12.19, 8)	4m 23s
testLatestScala (Native, 2.12.19, 21)	4m 15s
testLatestScala (Native, 2.13.13, 8)	4m 5s
testLatestScala (Native, 2.13.13, 21)	4m 9s
	1h 25m 47s

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