feat(tests): restore manual pid allowance for capturing events

[solnic]

Closes #1052

[sentry]

Bug: The pattern match for NimbleOwnership.fetch_owner/3 is incorrect. It expects {:ok, owner_pid} but receives {:ok, {pid, metadata}}, causing a runtime error in subsequent calls.
_{Severity: HIGH}

Suggested Fix

Update the case statement in find_collector/0. The success clause should pattern match on {:ok, {owner_pid, _metadata}} to correctly extract the owner_pid. The error clause should match {:error, _reason} to correctly handle cases where no owner is found and avoid a CaseClauseError.

Prompt for AI Agent

Review the code at the location below. A potential bug has been identified by an AI
agent. Verify if this is a real issue. If it is, propose a fix; if not, explain why it's
not valid.

Location: lib/sentry/test.ex#L818-L822

Potential issue: The `find_collector/0` function incorrectly pattern-matches the return
value from `NimbleOwnership.fetch_owner/3`. According to NimbleOwnership v1.0
documentation, `fetch_owner/3` returns `{:ok, {owner_pid, metadata}}`. However, the code
at line 818 matches `{:ok, owner_pid}`, which incorrectly binds the variable `owner_pid`
to the tuple `{actual_pid, metadata}`. This tuple is then passed as the `owner` argument
to `NimbleOwnership.get_owned/3`, which expects a PID, leading to a runtime failure.
Additionally, the `case` statement's error handling clause incorrectly matches `:error`
instead of `{:error, reason}`, which will raise a `CaseClauseError` if no owner is
found. This will cause all event collection in test mode to fail.

_{Did we get this right? 👍 / 👎 to inform future reviews.}