fix: Conditional checks for PROTONVPN_TIER

[tkimball83]

What does this do / why do we need it?

Using CFG_TIER in 'run' returns an empty value causing immediate failures. Use PROTONVPN_TIER as documented instead.

How this PR fixes the problem?

+ [[ '' -lt 1 ]]
+ log_error 'Using P2P requires basic plan or above!'
+ __logger_core_event_handler error 'Using P2P requires basic plan or above!'

2021-09-23 19:30:36+00:00 [INFO ] PROTONVPN_CHECK_INTERVAL is set to #60
2021-09-23 19:30:36+00:00 [INFO ] Reconnect threshold is #3
2021-09-23 19:30:36+00:00 [INFO ] Checking orphaned openvpn process
2021-09-23 19:30:36+00:00 [INFO ] This appears to be a fresh start!
2021-09-23 19:30:36+00:00 [ERROR ] Using P2P requires basic plan or above!
2021-09-23 19:30:37+00:00 [INFO ] PROTONVPN_CHECK_INTERVAL is set to #60
2021-09-23 19:30:37+00:00 [INFO ] Reconnect threshold is #3
2021-09-23 19:30:37+00:00 [INFO ] Checking orphaned openvpn process
2021-09-23 19:30:37+00:00 [INFO ] This appears to be a fresh start!
2021-09-23 19:30:37+00:00 [ERROR ] Using P2P requires basic plan or above!
2021-09-23 19:30:38+00:00 [INFO ] PROTONVPN_CHECK_INTERVAL is set to #60
2021-09-23 19:30:38+00:00 [INFO ] Reconnect threshold is #3
2021-09-23 19:30:38+00:00 [INFO ] Checking orphaned openvpn process
2021-09-23 19:30:38+00:00 [INFO ] This appears to be a fresh start!
2021-09-23 19:30:38+00:00 [ERROR ] Using P2P requires basic plan or above!

Additional Comments (if any)

Another workaround is to define CFG_TIER as a container environment variable.