Fix parameter filtering in the batch telemetry sample dashboard

[Kenny Saelen (kennysaelen)]

The Environment Id, Batch Job Id and Activity Id parameters on the batch dashboard did not filter correctly. Most of the issues were field-name casing mismatches between the tile queries and the values the parameter lookup queries actually return, which caused tiles to silently return no rows when a parameter was selected.

Fixed

• Environment Id matched nothing and blanked all 13 tiles. Tiles filtered on customDimensionsParsed.EnvironmentId, but the emitted field is environmentId (lowercase e) — the casing the parameter's own lookup query already reads.
• The Batch Infolog Errors query failed outright on cvustomDimensionsParsed.EnvironmentId, an undefined identifier — an error rather than an empty result.
• The Batch server #tasks execution spread pie blanked on job selection, reading customDimensionsParsed.batchJobId where the emitted field is BatchJobId.
• Environment Id ignored multi-select. Declared selectionType: array, but filtered with scalar == _environmentId; correct for one selection, wrong for several. Now in (_environmentId).
• The Activity Id parameter did nothing — declared but referenced by no tile. Now applied to Batch execution history, which already exposed an ActivityId column.
• The Activity Id value list came from pageViews, client/UI telemetry with no batch activity ids, so the picker offered values that could never match. Now sourced from batch customEvents.
• The Environment Id value list ignored the dashboard time range, being hardcoded to ago(7d) .. now(). With a wider time range, environments present only in the older window were missing from the picker even though the tiles filtered on them correctly. All 16 queries now share the dashboard time range.

Changed

• Batch Job Id now supports multi-select (scalar → array). No query changes were required — the filtering tiles already used in (_batchJobId).
• The Activity Id value list now includes BatchJobStart and BatchJobFinished, so activity ids appearing only on job-level events are selectable.

Added

• Dashboards/AzureDataExplorer/CHANGELOG.md, seeded with the above.

Result

All three parameters are now consistent: array selection with includeAllOption, in (...) membership filters guarded by isempty(), and lookup queries bound to the dashboard time range.

Note: the ADX query editor may report a semantic error on _startTime / _endTime in a parameter lookup query until that query has been run once from within the parameter editor. The variables do resolve correctly at runtime.

Note for reviewers

With Batch Job Id multi-select enabled, Batch server #tasks execution spread and Batch execution history aggregate across all selected jobs.

Verified by importing the dashboard into Azure Data Explorer.