Update make e2e test so that you only need the test name

[chatton]

Description

This PR fixes two small things with the e2e running script.

1. You now only need to provide a single argument to make e2e-test

e.g.

make e2e-test test=TestMaxExpectedTimePerBlockParam

The entrypoint will be automatically be determined using jq. If jq is not present it will require the entrypoint to be specified as usual.

2. The logs now display as the test is running, instead of after the test finishes. This is achieved by providing a single file name rather than ./... to go test.

closes: #3255

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[chatton]

TEST is required, but ENTRY_POINT is not

[damiannolan]

Really nice improvement! ❤️

Let us all bow to the jq gods 🙇

[colin-axner]

More 🧙! I love it!