fix(calendar): revert removal of workaround for virtual repeat issue

[Splaktar]

PR Checklist

Please check that your PR fulfills the following requirements:

• The commit message follows our guidelines
• Tests for the changes have been added or this is not a bug fix / enhancement
• Docs have been added, updated, or were not required

PR Type

What kind of change does this PR introduce?

[x] Bugfix
[ ] Enhancement
[ ] Documentation content changes
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Infrastructure changes
[ ] Other... Please describe:

What is the current behavior?

md-calendar when used outside of md-datepicker doesn't scroll to the current month and stays on January 1880.

Issue Number:
Fixes #11919

What is the new behavior?

• revert removal of workaround for virtual repeat issue
  • Virtual repeat not scrolling to the top index on load #8585 turned out to not be a bug
  • this restored code is not actually a workaround for a bug but actually part of the implementation needed for md-calendar
• improve some types and JSDoc

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

This is a regression fix for an issue with PR #11906 that has not yet been part of a release.

[mmalerba]

LGTM