test: make cloudflare fake claims deterministic

[pinheadmz]

Closes #516
Resolves a5cc393

There are several tests that make "fake" reserved name claims in order to test the HNS reserved name claim system. That system looks up actual, real-world, ICANN-rooted DNS records and checks the DNSSEC chain. The only thing "fake" about the tests is that once we download the actual live DNSSEC chain, the test inserts a wallet claim such as this into the cloudflare.com zone:

cloudflare.com. 300 IN TXT "hns-regtest:aakbvmygsp7rrhmsauhwlnwx6srd5m2v4m3p3eidadl5yn2f"

Of course this invalidates the RRSIG TXT in that zone, but we have a bypass just for this precise case so we can test everything else:

hsd/test/auction-reorg-test.js

Lines 454 to 459 in 7826128

	try {
	ownership.ignore = true;
	assert(await chain.add(block));
	} finally {
	ownership.ignore = false;
	}

The issue is that now the test suite is dependent on the runner's ability to access the internet, and lookup the cloudflare.com DNS zone. I think that is OK -- since the ability to do so is also crucial for the HNS reserved name claims system to work.

What this PR fixes is a set value that the fake claim redeems by claiming cloudflare on regtest. The claim still pays a fee, which is an amount of HNS based on the size of the claim (just like any other type of transaction). However, cloudflare is welcome to change their DNS records at any time -- add or remove TXT in their zone, sign RRSIGs with different key algorithms, etc. This means we can not predetermine the size of the fake claim for the test and therefore can not assert that a specific value of HNS will be redeemed by submitting the claim on regtest.

Solution: set the fee rate to zero :-)

[coveralls]

Pull Request Test Coverage Report for Build 267283005

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 5 unchanged lines in 3 files lost coverage.
• Overall coverage increased (+0.1%) to 59.367%

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Files with Coverage Reduction	New Missed Lines	%
lib/net/pool.js	1	32.63%
lib/net/peer.js	2	35.28%
lib/wallet/wallet.js	2	70.0%

Totals
Change from base Build 238010293:	0.1%
Covered Lines:	19423
Relevant Lines:	30471

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💛 - Coveralls

[ca98am79]

Tested ACK - works for me