Move existing logs in `/opt/<component>/var/log` to `/var/log/<component>` pre-upgrade

[zrhoffman]

The symlinks created in #7999 work, but only for fresh installs, not upgrades. #8001 fixes that by

• Moving existing logs in /opt/<component>/var/log to /var/log/<component>
• Not creating a symlink inside the symlink target if the symlink target already exists and is a directory

  ---

Which Traffic Control components are affected by this PR?

• Traffic Monitor
• Traffic Router
• Traffic Stats

What is the best way to verify this PR?

1. Build the RPMs

   ./pkg -v traffic_monitor_build traffic_stats_build traffic_router_build

2. Verify that files that exist in the old log directories pre-install are moved to the new log directories

   <<'SHELL_COMMANDS' docker run --rm -i -v $(pwd)/dist:/dist rockylinux:8 bash
   set -o errexit
   mkdir -p /opt/traffic_{monitor,stats,router}/var/log
   touch /opt/traffic_{monitor,stats,router}/var/log/my-logfile.log
   rpm -Uvh --nodeps dist/traffic_monitor-8.1.0-12410.cff72c19.el8.x86_64.rpm dist/traffic_router-8.1.0-12410.cff72c19.el8.noarch.rpm dist/traffic_stats-8.1.0-12410.cff72c19.el8.x86_64.rpm
   ls -1 /var/log/traffic_{monitor,stats,router}/my-logfile.log
   SHELL_COMMANDS

   Expected output:

   /var/log/traffic_monitor/my-logfile.log
   /var/log/traffic_router/my-logfile.log
   /var/log/traffic_stats/my-logfile.log

PR submission checklist

• [ ] This PR has tests
• [ ] This PR has documentation
• [ ] This PR has a CHANGELOG.md entry
• [x] This PR DOES NOT FIX A SERIOUS SECURITY VULNERABILITY (see the Apache Software Foundation's security guidelines for details)