[WIP] feat: default preload false in ci

[alanshaw]

BREAKING CHANGE: Content preloading on preload nodes is now disabled by default in test and CI environments. This can be overridden by explicitly enabling preloading in test/CI by setting preload.enabled to true in the IPFS constructor args.

resolves #1815

cc @eefahy

[achingbrain]

Couldn't we configure this as part of the build environment or during the test suite setup instead of changing the application code to have test-specific code paths?

[alanshaw]

We could, but this also mitigates against preload happening when run in CI by people using js-ipfs in their applications.

[daviddias]

👍 from me. I don't necessarily agree that this should be classified as a breaking change. The users of this module will have to do zero changes to their codebase and there won't be any behavior change for them. That said, I'm also not opposed if you feel strongly about it :)

[alanshaw]

The users of this module will have to do zero changes to their codebase

In production, no, but if users have integration tests that rely on two nodes exchanging content via the preload nodes then they'll need to explicitly set preload to true.

What is "breaking" anyway? 😆

[alanshaw]

...need to fix the browser issues before this can be merged