[backport -> release/3.6.x] fix(wasm): do not call attach() on re-entrancy

[team-gateway-bot]

Automated backport to release/3.6.x, triggered by a label in #12402.

Original description

Summary

kong.runloop.wasm.attach() may be called more than once when filters utilize the dispatch_http_call proxy-wasm SDK function. Previously this was assumed to be false, which can yield errors like this one:

2024-01-22 16:39:16 2024/01/22 22:39:16 [crit] 2464#0: *340 [lua] wasm.lua:790: attach(): failed attaching service(6bc44ccb-30c9-5f3d-acfa-017fa1b2ef82) filter chain to request: previous plan already attached, client: 172.17.0.1, server: kong, request: "GET /anything HTTP/1.1", host: "localhost:8000", request_id: "112ec236dcf487391a579a6f6f63fc0b"

This adds a ngx.ctx check and avoids calling proxy_wasm.attach() in this case.

Unfortunately it is incredibly non-trivial to add a test case for this at the moment, but the behavior change/correctness has been validated by hand.

Checklist

• The Pull Request has tests
• A changelog file has been created under changelog/unreleased/kong or skip-changelog label added on PR if changelog is unnecessary. README.md
• There is a user-facing docs PR

Issue reference

KAG-3603

[locao]

Waiting for a green run before merging.

[team-gateway-bot]

Cherry-pick failed for release/3.6.x: couldn't find remote ref release/3.6.x.
Please ensure that this Github repo has a branch named release/3.6.x.

[team-gateway-bot]

Cherry-pick failed for release/3.6.x, because it was unable to create a new branch.

Please cherry-pick the changes locally.

git remote add upstream https://github.com/kong/kong-ee
git fetch upstream release/3.6.x
git worktree add -d .worktree/cherry-pick-12452-to-release/3.6.x-to-upstream upstream/release/3.6.x
cd .worktree/cherry-pick-12452-to-release/3.6.x-to-upstream
git checkout -b cherry-pick-12452-to-release/3.6.x-to-upstream
ancref=$(git merge-base 6cf74cdabf97e672569f3be9b3ec502be6b56219 1edb16b1349c796bfe55ae0553a4712d4a703305)
git cherry-pick -x $ancref..1edb16b1349c796bfe55ae0553a4712d4a703305

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edit (@flrgh): backporting from this PR instead