Update MAX_LTS_SUPPORTED_BY_KOTLIN to 21 #35600

Job	Run time
Attach pull request number	2s
Initial JDK 11 Build	11m 32s
CI Sanity Check	31s
Calculate Test Jobs	10s
Maven Tests - JDK 11	57m 34s
JVM Tests - JDK 11	1h 19m 21s
Maven Tests - JDK 11 Windows	1h 10m 34s
JVM Tests - JDK 17	3h 40m 1s
Gradle Tests - JDK 11	26m 43s
Devtools Tests - JDK 11	15m 13s
Gradle Tests - JDK 11 Windows	53m 8s
JVM Tests - JDK 21	3h 38m 3s
Kubernetes Tests - JDK 11	3m 37s
Devtools Tests - JDK 17	14m 38s
JVM Tests - JDK 17 Windows	48m 41s
Kubernetes Tests - JDK 17	3m 3s
Devtools Tests - JDK 11 Windows	22m 3s
Quickstarts Compilation - JDK 17	5m 55s
Kubernetes Tests - JDK 11 Windows	2m 25s
Native Tests - Virtual Thread - Main	22m 52s
Native Tests - Virtual Thread - Messaging	9m 37s
MicroProfile TCKs Tests	6m 51s
Native Tests - Main	6m 19s
Native Tests - Data1	28m 45s
Native Tests - Data2	24m 50s
Native Tests - Data3	21m 54s
Native Tests - Data4	16m 59s
Native Tests - Data5	20m 53s
Native Tests - Data6	25m 34s
Native Tests - Data7	34m 17s
Native Tests - Amazon	15m 18s
Native Tests - Messaging1	24m 13s
Native Tests - Messaging2	18m 24s
Native Tests - Security1	23m 9s
Native Tests - Security2	27m 57s
Native Tests - Security3	11m 38s
Native Tests - Cache	15m 36s
Native Tests - HTTP	37m 19s
Native Tests - Misc1	27m 42s
Native Tests - Misc2	16m 56s
Native Tests - Misc3	33m 59s
Native Tests - Misc4	43m 23s
Native Tests - Spring	18m 6s
Native Tests - gRPC	18m 18s
Native Tests - Windows - RESTEasy Jackson	5m 7s
Native Tests - DevTools Integration Tests	4m 46s
Native Tests - AWT, ImageIO and Java2D	8m 11s
Build report	1m 35s
	23h 43m 42s

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