chore: bump lambda layer size limit for ddtrace 4.15.x

The zipped layer size check started failing at 9273 kb against the 9231 kb
limit. This is unrelated to any source change in this branch: the ddtrace
cp311 manylinux x86_64 wheel grew ~470 kb in 4.15.0 (8.87 MB in 4.14.2 ->
9.33 MB in 4.15.0), and pyproject.toml pins ddtrace ">=4.1.1,<5,!=4.6.*"
with no upper bound inside 4.x, so CI resolves to the newest 4.15.x.

Raise MAX_LAYER_COMPRESSED_SIZE_KB from 9*1024+15 (9231 KB) to 9*1024+128
(9344 KB), which clears the observed 9273 kb with ~71 kb of headroom while
keeping the guardrail tight enough to catch further growth. x86_64 is the
larger of the two published arches (~245 kb above aarch64), so the failing
cp311 x86_64 job is the worst case across the build matrix.

The uncompressed limit is unchanged.

Author: jeastham1993

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 + 128)      # 9344 KB
 MAX_LAYER_UNCOMPRESSED_SIZE_KB=$(expr 25 \* 1024)   # 25600 KB