chore: raise compressed layer size limit to 9728 KB

ddtrace 4.15.x grew the amd64 layers past the 9231 KB limit (3.14-amd64
is 9538 KB, 3.11-3.13 are 9238-9283 KB). Nearly all of the growth is in
ddtrace's native extension (_native.so, +401 KB compressed), led by
DataDog/dd-trace-py#19631 (+233 KB).

Raise the limit to 9.5 MB to unblock CI while the size regression is
addressed upstream.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

Author: joeyzhao2018

scripts/check_layer_size.sh

@@ -8,7 +8,7 @@
 # Compares layer size to threshold, and fails if below that threshold
 
 set -e
-MAX_LAYER_COMPRESSED_SIZE_KB=$(expr 9 \* 1024 + 15)      # 9231 KB
+MAX_LAYER_COMPRESSED_SIZE_KB=$(expr 9 \* 1024 + 512)     # 9728 KB
 MAX_LAYER_UNCOMPRESSED_SIZE_KB=$(expr 25 \* 1024)   # 25600 KB