CI: Remove vestigial shell function wrapper

This shell function exists only within the scope of the shell. The
python script is entirely unaware of it.

(Introduced in da52dace85).

Signed-off-by: Samuel Dionne-Riel <samuel@dionne-riel.com>
Part-of: https://gitlab.postmarketos.org/postmarketOS/pmaports/-/merge_requests/6330
[ci:skip-build]: already built successfully in CI

.ci/apkbuild-lint.sh

@@ -11,12 +11,4 @@ if [ "$(id -u)" = 0 ]; then
 	exec su "${TESTUSER:-pmos}" -c "sh -e $0"
 fi
 
-# Wrap pmbootstrap to use this repository for --aports
-pmaports="$(cd "$(dirname "$0")"/..; pwd -P)"
-_pmbootstrap="$(command -v pmbootstrap)"
-pmbootstrap() {
-	"$_pmbootstrap" --aports="$pmaports" "$@"
-}
-
 .ci/lib/apkbuild_linting.py
-