Fix Slow DevMode Test (TestDevMode)

[winder]

Subject of the issue

This test is inexplicably slow and ends up failing periodically. This could be a byproduct of the environment it's running in or a problem that needs to be resolved.

The test is fairly straightforward. It submits 2 transactions and checks that they are confirmed faster than 2x the normal confirmation time.

Here is the failure:

=== RUN   TestDevMode
Created new rootkey: /opt/cibuild/project/tmp/out/e2e/128713-1638452531109/go/TestDevMode/Wallet3.rootkey
Created new rootkey: /opt/cibuild/project/tmp/out/e2e/128713-1638452531109/go/TestDevMode/Wallet2.rootkey
Created new rootkey: /opt/cibuild/project/tmp/out/e2e/128713-1638452531109/go/TestDevMode/Wallet1.rootkey
Created new partkey: /opt/cibuild/project/tmp/out/e2e/128713-1638452531109/go/TestDevMode/Wallet3.0.3000000.partkey
Created new partkey: /opt/cibuild/project/tmp/out/e2e/128713-1638452531109/go/TestDevMode/Wallet2.0.3000000.partkey
Created new partkey: /opt/cibuild/project/tmp/out/e2e/128713-1638452531109/go/TestDevMode/Wallet1.0.3000000.partkey
https://github.com/algorandfoundation/specs/tree/bc36005dbd776e6d1eaf0c560619bb183215645c 100000
algod(5283) : No REST API Token found. Generated token: 7d404e1a5dd5e71e2eae2cd5e0eb34cdf892bf5b6045347424cb0f20fa126df3
algod(5283) : No Admin REST API Token found. Generated token: 137d564df72ca487dd8be53977277bda38b71b3c00cfa4774a9f4f39be5a4211
algod(5283) : Logging to:  /opt/cibuild/project/tmp/out/e2e/128713-1638452531109/go/TestDevMode/Node/node.log
algod(5283) : Deadlock detection is set to: enabled (Default state is 'enable')
algod(5283) : Initializing the Algorand node... 
algod(5283) : Success!
algod(5283) : ⇨ http server started on 127.0.0.1:8080
algod(5283) : Node running and accepting RPC requests over HTTP on port 127.0.0.1:8080. Press Ctrl-C to exit
    devmode_test.go:58: 
        	Error Trace:	devmode_test.go:58
        	Error:      	Should be true
        	Test:       	TestDevMode
        	Messages:   	Transactions should be quickly confirmed faster than usual.
algod(5283) : Exiting on terminated
--- FAIL: TestDevMode (19.20s)