[WIP] Remove tesnet flows

[minghinmatthewlam]

Why this should be merged

Removes testnet e2e flows that we don't use and is extra burden to maintain. Mostly will rely on local network e2e tests, only main difference with testing on testnet is the difference in the networks, so confirming in manual deployments of Teleporter's interaction with Warp and network validators should cover

How this works

still leaves e2e test that allow for non local networks being passed. Might be useful when we want to manually set up testnet testing.

How this was tested

How is this documented

[geoff-vball]

LGTM. I think the upload tmpnet files step just needs to be fixed

[minghinmatthewlam]

deferring for now to fully handle removing #498 (comment)

[iansuvak]

I like the simplification with removal of interfaces and resulting shrinking of the utils file.

FWIW I didn't mind the earlier commit you had with n instead of localnetwork either but this works too.

[cam-schultz]

Overall lgtm, just one request to put the LocalNetwork methods all in the same place.

[cam-schultz]

Can we move the LocalNetwork methods in this file to tests/network/network.go with all the others?