Remove unused get_main_pkgs.sh script (#6555)

This PR removes the `get_main_pkgs.sh` script as it is no longer used in
the project.

Closes #6526.

---------

Co-authored-by: Damien Mathieu <42@dmathieu.com>

get_main_pkgs.sh

@@ -1,30 +0,0 @@
-#!/usr/bin/env bash
-
-# Copyright The OpenTelemetry Authors
-# SPDX-License-Identifier: Apache-2.0
-
-set -euo pipefail
-
-top_dir='.'
-if [[ $# -gt 0 ]]; then
-    top_dir="${1}"
-fi
-
-p=$(pwd)
-mod_dirs=()
-
-# Note `mapfile` does not exist in older bash versions:
-# https://stackoverflow.com/questions/41475261/need-alternative-to-readarray-mapfile-for-script-on-older-version-of-bash
-
-while IFS= read -r line; do
-    mod_dirs+=("$line")
-done < <(find "${top_dir}" -type f -name 'go.mod' -exec dirname {} \; | sort)
-
-for mod_dir in "${mod_dirs[@]}"; do
-    cd "${mod_dir}"
-
-    while IFS= read -r line; do
-        echo ".${line#${p}}"
-    done < <(go list --find -f '{{.Name}}|{{.Dir}}' ./... | grep '^main|' | cut -f 2- -d '|')
-    cd "${p}"
-done