cleanup: replace erase-remove idiom with std::erase_if or absl::erase_if

[Amila-Rukshan]

Description

Replace the traditional erase-remove idiom with the more concise std::erase_if and absl::erase_if APIs where applicable.

This improves readability by expressing the intent to remove elements matching a predicate directly, while preserving the existing behavior.

Changes

Replace std::remove_if followed by erase with std::erase_if for standard containers.
Replace the same pattern with absl::erase_if for supported Abseil containers.

No functional behavior changes are intended.

[Amila-Rukshan]

/retest

[Copilot]

Pull request overview

This PR modernizes element-removal code paths across Envoy by replacing the erase-remove idiom with std::erase_if (for standard containers) and absl::erase_if (for Abseil containers), improving readability while aiming to preserve behavior.

Changes:

• Replaced container.erase(std::remove_if(...), end()) with std::erase_if(container, pred) for standard containers.
• Replaced the equivalent pattern with absl::erase_if(container, pred) for Abseil containers.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
test/server/config_validation/xds_verifier.cc	Uses std::erase_if to remove listener entries marked REMOVED in both SOTW and delta update paths.
test/server/config_validation/xds_fuzz.cc	Uses std::erase_if to remove listeners by name in fuzz test helper.
source/extensions/filters/http/cache_v2/cache_sessions_impl.cc	Uses std::erase_if to remove out-of-range body subscribers while performing existing side effects.
source/extensions/clusters/dynamic_forward_proxy/cluster.cc	Uses std::erase_if to remove draining connection entries from the per-key connection info vector.
source/extensions/bootstrap/reverse_tunnel/downstream_socket_interface/reverse_connection_io_handle.cc	Uses std::erase_if to remove stale connection wrappers from the wrappers vector.
source/common/upstream/upstream_impl.cc	Uses std::erase_if to prune host vectors in dynamic host list update logic.
source/common/upstream/cluster_manager_impl.cc	Uses std::erase_if to remove hosts from hosts_added_ that are also in hosts_removed_.
source/common/http/http_server_properties_cache_impl.cc	Uses std::erase_if to drop expired alternate protocols while preserving existing update behavior.
source/common/http/header_map_impl.h	Switches removal on absl::InlinedVector to absl::erase_if (with a now-outdated explanatory comment).
source/common/event/evwatch_observer_manager_impl.cc	Uses std::erase_if to purge nulled observer entries from the observer list.

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[botengyao]

thanks for the improvement, lgtm module the nit.

/wait

[Amila-Rukshan]

@botengyao, @wbpcode, I have addressed the nit.