Remove obsolete chromeosInfoPrivate.isRunningOnLacros

Lacros is gone, this function is not used anymore.

Bug: b:354842935
AX-Relnotes: n/a.
Change-Id: Idcae62bfb8e2922c63d5c74f5e9e0e3c66258ac4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6255537
Commit-Queue: Georg Neis <neis@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Reviewed-by: John Lee <johntlee@chromium.org>
Reviewed-by: Takashi Toyoshima <toyoshim@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1420317}
NOKEYCHECK=True
GitOrigin-RevId: ff2b2c0a11ade459923910020cfce62ea63224bf