install-deps.sh: import ubuntu-toolchain-r's key without keyserver

install-deps.sh: import ubuntu-toolchain-r's key without keyserver

we are running into following error recently

gpg: requesting key BA9EF27F from hkp server keyserver.ubuntu.com
gpgkeys: key 1E9377A2BA9EF27F can't be retrieved
gpg: no valid OpenPGP data found.
gpg: Total number processed: 0
gpg: keyserver communications error: keyserver helper general error
gpg: keyserver communications error: unknown pubkey algorithm
gpg: keyserver receive failed: unknown pubkey algorithm

so use the local copy of the pubkey instead

Signed-off-by: Kefu Chai <kchai@redhat.com>