Linux: Change repo config to use HTTPS.

This is bad for caching but defense-in-depth for security.

Change-Id: I95140fcd58fd66f643cdc1b92483bd2ca6087f4a
Fixed: 1228470
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3114227
Auto-Submit: Joshua Pawlicki <waffles@chromium.org>
Commit-Queue: Thomas Anderson <thomasanderson@chromium.org>
Reviewed-by: Thomas Anderson <thomasanderson@chromium.org>
Cr-Commit-Position: refs/heads/main@{#914409}

chrome/installer/linux/rpm/build.sh

@@ -234,7 +234,7 @@ fi
 eval $(sed -e "s/^\([^=]\+\)=\(.*\)$/export \1='\2'/" \
   "${OUTPUTDIR}/installer/theme/BRANDING")
 
-REPOCONFIG="http://dl.google.com/linux/${PACKAGE#google-}/rpm/stable"
+REPOCONFIG="https://dl.google.com/linux/${PACKAGE#google-}/rpm/stable"
 verify_channel
 export USR_BIN_SYMLINK_NAME="${PACKAGE}-${CHANNEL}"