EC2Architect - Various small improvements

[JackUrb]

Overview

In more testing, ran into two primary issues:

1. With tmux sessions sometimes the ssh-agent forwarding would become stale and then setting up the server would hang indefinitely.
2. Determining the priority to use based on the number of rules meant that if some servers shut down (reducing the rule number) and then more were launched, two servers could attempt to be launched with the same rule priority.
3. The subdomain string could contain special characters not allowed by amazon

Implementation

1. Clearing SSH_AUTH_SOCK in the env overwrites use of the ssh-agent for auth (which we don't need as we're referring to the .pem keypair anyways), which should resolve tmux issues (can't directly reproduce yet).
2. Implements a search over possible priority numbers
3. Runs a regex replace to remove special characters from the provided subdomain
4. Also adds an Owner tag to all resources, to make them easier to track

cc @klshuster @ytsheng

[codecov-commenter]

Codecov Report

Merging #609 (8aec981) into main (e70e460) will increase coverage by 0.06%.
The diff coverage is 25.00%.

@@            Coverage Diff             @@
##             main     #609      +/-   ##
==========================================
+ Coverage   63.20%   63.26%   +0.06%     
==========================================
  Files          86       86              
  Lines        8221     8230       +9     
==========================================
+ Hits         5196     5207      +11     
+ Misses       3025     3023       -2     

Impacted Files	Coverage Δ
...histo/abstractions/architects/ec2/ec2_architect.py	35.71% <25.00%> (-0.06%)	⬇️
...ephisto/abstractions/architects/ec2/ec2_helpers.py	17.48% <25.00%> (+0.29%)	⬆️
mephisto/operations/supervisor.py	79.65% <0.00%> (+0.64%)	⬆️
...tractions/architects/channels/websocket_channel.py	80.23% <0.00%> (+1.16%)	⬆️
mephisto/abstractions/architects/mock_architect.py	91.50% <0.00%> (+2.61%)	⬆️

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[JackUrb]

Merging without review after testing, to get as many people on the bugless version as possible.