[willum070]

Co-authored by @zigzag. Thanks for finding this fix and submitting PR #1734! This PR patches the changes so that our internal processes can be run.

Issue:

The two button variable names in samples/control-custom-state/index.ts were swapped relative to their actual behavior. setCenterButton was bound to btnCenterMap (the button that recenters the map) but only applies the stored center, so it doesn't "set" anything.
resetCenterButton was bound to btnSetCenter (the button that stores the current center) but is the one that actually stores it, so it doesn't "reset" anything.

Changes made:

1. Renamed setCenterButton to centerMapButton (bound to btnCenterMap)
2. Renamed resetCenterButton to setCenterButton (bound to btnSetCenter)
3. Updated only identifiers to match the HTML ids/labels and what each click handler actually does. No behavior change.

Change-Id: I99ba8df327b6c168c15e51b3e09889687870db68