Commit Message:

Angle brackets are not required after constructor and, maybe, aren't even correct, though I'm not 100% sure on what the standard says on the matter.

It seems like clang is fine with this syntax, but when you try to build Envoy with gcc it complains:

./contrib/postgres_proxy/filters/network/source/postgres_message.h: At global scope:
./contrib/postgres_proxy/filters/network/source/postgres_message.h:397:14: error: expected unqualified-id before ')' token
  397 |   Sequence<>() = default;
      |              ^
Target //contrib/exe:envoy-static failed to build

Given that it's at least unusual to have angle brackets after constructor in a class template specialization let's remove them and satisfy both gcc and clang.

Additional Description:

It's one of the issue that prevent contrib build with gcc. It's not the original issue reported in #31807, but that issue is what started the investigation.

Risk Level: Low
Testing: bazel build with --config=gcc and --config=docker-gcc options and in various compliation modes.
Docs Changes: N/A
Release Notes: N/A
Platform Specific Features: N/A

Request variables

Key	Value
ref	daaf756
sha	0e250f8
pr	37038
base-sha	01d94d2
actor	@krinkinmu
message	[contrib][postgres] Remove <> after constructor in the PG proxy code...
started	1730999238.843967
target-branch	main
trusted	false

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Envoy version (as used in this CI run)