remove weak function declaration of tud_msc_is_writable_cb to fix simultaneous CDC and MSC #4114

Job	Run time
Push event file	3s
Generate matrix	4s
Build (validation, esp32c6) / Build validation tests for esp32c6	4m 34s
Build (validation, esp32c3) / Build validation tests for esp32c3	4m 5s
Build (validation, esp32) / Build validation tests for esp32	5m 41s
Build (validation, esp32h2) / Build validation tests for esp32h2	3m 34s
Build (validation, esp32p4) / Build validation tests for esp32p4	4m 2s
Build (validation, esp32s2) / Build validation tests for esp32s2	5m 21s
Build (validation, esp32s3) / Build validation tests for esp32s3	6m 30s
QEMU	0s
Hardware	0s
	33m 54s

Provide feedback