Net 137 relays

[abhishek9686]

Describe your changes

-> Remove Drop rules
-> Set Foward Policy to Accept by default

Provide Issue ticket number if applicable/not in title

Provide link to Netmaker PR if required

gravitl/netmaker#2401

Provide testing steps

• Start with a single network
  a. Relay a Node
  b. Relay two Nodes with same Relay Node
  c. while Nodes are being relayed, make a node as a ingress gateway, check whether ext clients are able to reach relayed Nodes
  d. Test egress behind a relay
• Test relays on multiple networks, with repeating above steps

Checklist before requesting a review

• My changes affect only 10 files or less.
• I have performed a self-review of my code and tested it.
• If it is a new feature, I have added thorough tests, my code is <= 1450 lines.
• If it is a bugfix, my code is <= 200 lines.
• My functions are <= 80 lines.
• I have had my code reviewed by a peer.
• My unit tests pass locally.
• Netclient & Netmaker are awesome.