DOCS-1830 - Differentiate and consolidate time-range documentation

[JV0812]

Purpose of this pull request

This pull request differentiates and consolidates four docs covering overlapping time concepts, per the ticket.

Changes:

• time-range-expressions.md becomes the canonical page for relative/absolute time-range expression syntax. Added a new "General rules" section consolidating rules that were duplicated (and drifted) in set-time-range.md: 24-hour/12-hour time entry, mm/dd/yyyy date entry, Custom-picker quick-adjust abbreviations (with the m=minute vs. m=months distinction called out explicitly), and the Free-account 7-day time-range limit. Also folded in the Scheduled Search timezone caveat and browser-locale date-format caveat previously in time-reference.md, and fixed a pre-existing gap where the absolute-expression section never stated that a single expression's end time defaults to "now" (only the relative section said so, despite the original rule stating it applies to all time expressions). Added a "See also" section cross-linking to the other three docs.
• set-time-range.md trimmed to its own UI-picker mechanics only (Relative/Custom/Recent options, timezone-offset display details). Removed the duplicated "Rules" section and the Free-account sentence, now owned solely by time-range-expressions.md. Added a link to time-range-expressions.md for the actual syntax rules, and a note pointing to use-receipt-time.md/use-searchable-time.md for the "which timestamp field" question.
• time-reference.md trimmed to pure ingest-time timestamp parsing by removing its "Time ranges" and "Date format" sections, which strayed into Search-UI territory already covered elsewhere. Replaced with a short pointer note so its ~35 inbound links still land on a coherent page.
• use-receipt-time.md and use-searchable-time.md each get a disambiguation note clarifying they're two of three timestamp-field options (message time is the default), cross-linking to each other and to set-time-range.md.

No sidebar, redirect, or ID/slug changes. Verified via full yarn build (no broken links/anchors) and a line-by-line audit confirming every original rule from the removed sections is still captured somewhere.

Select the type of change

• Minor Changes - Typos, formatting, slight revisions
• Update Content - Revisions, updating sections
• New Content - New features, sections, pages, tutorials
• Site and Tools - .clabot, version updates, maintenance, dependencies, new packages for the site (Docusaurus, Gatsby, React, etc.)

Ticket (if applicable)

https://sumologic.atlassian.net/browse/DOCS-1830

[kimsauce]

Suggested change

	## See also
	## Additional resources

[kimsauce]

@JV0812 Shouldn't this Date format section stay in there? It's in the title, and I don't see other guidance like that elsewhere in the doc.