docs: audit selector tables for values column consistency (follow-up to #9238)

[ebylund]

Summary

Follow-up to #9238 per reviewer suggestion on review 4163017606: batch a values-column audit for the telemetry selector tables so the convention applied to is_primary_response in #9238 is consistent across all selectors.

Context

In #9238, the is_primary_response values column in selectors.mdx changed from true | false to just true, because the underlying selector only matches its guard when the config value is true (the false form either evaluates via a fallback arm or is not meaningful). Other selectors in the same and related tables use the true | false shape without the same nuance; a batched pass would align them.

Scope

Audit the selector tables in:

• docs/source/routing/observability/router-telemetry-otel/enabling-telemetry/selectors.mdx — router, supergraph, subgraph, connector, and related sections.

For each row currently documented with true | false:

1. Grep the corresponding selector variant in apollo-router/src/plugins/telemetry/config_new/**/selectors.rs.
2. Check whether the runtime guard matches only true, or treats true and false as two distinct meaningful paths.
3. Update the values column to true only if false isn't a meaningful separate configuration (falls back to default arm or never matches).

Candidates to check

(Non-exhaustive starting list — grep \| \.`.`true | false`inselectors.mdx` for the full set.)

• on_graphql_error
• is_deferred (will exist after #9241 lands — if only true is meaningful, land with the right convention from the start)
• Any other Boolean-guarded selector variants

Why batched

The per-selector audit requires reading the runtime guard for each variant. One focused PR is easier to review than threading the same check through every feature PR. Keeps individual feature PRs narrowly scoped to their code change.

Related

• #9238 — establishes the convention for is_primary_response
• #9241, #9242 — pending @defer telemetry work; new selectors they add should adopt whichever convention this audit confirms