fix: support createdFor org-scoping in user-creation-count report

[divyagovindaiah]

Summary

The Admin Reports "Total Users" widget calls POST /v1/observability/reports with reportId=user-creation-count and filters: { createdFor: <orgId> }. EsExecutor only ever read fromDate/toDate from the rendered query — createdFor was silently ignored.

This is a companion PR to a sunbird-spark-installer fix that adds createdFor to this report's supported_filters/query_template in standard_reports_meta (otherwise the request never even reaches EsExecutor — FilterValidator rejects it first with Unsupported filter(s): createdFor).

Why this isn't just a filter-name fix

Once the filter passes validation, EsExecutor still needs to use createdFor — otherwise the "Total Users" widget would silently return a platform-wide count instead of the count for the admin's own org, which is a correctness/data-exposure issue for an org-scoped admin view, not just a 400 error.

Fix

EsExecutor.execute() now also reads createdFor from the rendered query. When present, both rangeCount() and monthlyBreakdown() wrap their existing date-range query in a boolQuery().filter(termQuery("rootOrgId", createdFor)) — rootOrgId being the same field already used elsewhere in this codebase for org-scoped user lookups (e.g. UserDeletionBackgroundJobActor). Without createdFor, behavior is unchanged (platform-wide, as before).

Note for reviewers

I don't have this project's build environment set up locally, so this hasn't been compiled/tested here — please have CI/a reviewer verify it builds and the existing observability test suite (ObservabilityReportServiceSpec) still passes before merging.

Test plan

• Confirm build passes CI
• Call /v1/observability/reports with reportId=user-creation-count, filters: {createdFor: <orgId>} (no dates) — should return a monthly breakdown scoped to that org, not platform-wide
• Call with createdFor + fromDate/toDate together — should return a single org-scoped count for that range
• Call with no createdFor at all (existing behavior) — should be unchanged, platform-wide