[mono][arm] Fix rethrow instruction size (#76393)

It is the same as throw

Co-authored-by: Vlad Brezae <[email protected]>

Author: github-actions[bot]

src/mono/mono/mini/cpu-arm.mdesc

@@ -60,7 +60,7 @@ seq_point: len:52 clob:c
 il_seq_point: len:0
 
 throw: src1:i len:24
-rethrow: src1:i len:20
+rethrow: src1:i len:24
 start_handler: len:20
 endfinally: len:32
 call_handler: len:16 clob:c