Commit Message:

Clang and gcc are subtly different and it seems to be the cause of contrib build failures reported in
#31807 (e.g., when using gcc to link the final binary it results in a bunch of essential for gcc C++ symbols like __gxx_personality_v0).

This issue could be addressed (i.e., Envoy can be built using gcc). However, given that it only happens when we build ICU binary tools and those tools aren't used by Envoy directly or the build system, we can just not build them and address the issue this way.

Additional Description:

It addresses the immediate problem reported in #31807, but by itself it's not enough to fix gcc builds, so I'm not marking this PR as fixing that issue because of that, since ultimately we want to achieve successful gcc builds.

Risk Level: Low
Testing: building contrib and non-contrib Envoy using --config=gcc and --config=docker-gcc
Docs Changes: N/A
Release Notes: N/A
Platform Specific Features: N/A

Request variables

Key	Value
ref	eda7d87
sha	01a4bcc
pr	37039
base-sha	01d94d2
actor	@krinkinmu
message	[contrib] Stop building ICU tools to fix gcc Envoy build...
started	1731004750.830565
target-branch	main
trusted	false

Container image/s (as used in this CI run)

Envoy version (as used in this CI run)