Handle timeouts and properly cleanup memory

[Siegrift]

See discussion in #88 (comment)

Axios does not have any timeout by default. Ethers porovider has a 2 minute default timeout (but we can maybe set it explicitly). These are important to properly cleanup resources.

The go utils timeout can be applied as necessary. E.g. ensure that some loop calls do not overlap. This is tricky to do correctly because it's impossible to cancel running an already started function.

[Siegrift]

Also, fix this related comment https://github.com/api3dao/airseeker-v2/blob/fe884d446cd4150b7f1557355059c9a69291fc8f/src/signed-api-fetch/data-fetcher.ts#L92