Fix underpriced check for multi currency

[hbandura]

Fix the underpriced check by checking against all currency heaps

[github-actions[bot]]

Coverage from tests in ./e2e_test/... for ./consensus/istanbul/... at commit 8f49d7e7b6da5ef44722ad5119dc2c2c3d8a140a

coverage: 49.7% of statements across all listed packages

coverage:  63.2% of statements in consensus/istanbul
coverage:  42.7% of statements in consensus/istanbul/announce
coverage:  55.7% of statements in consensus/istanbul/backend
coverage:   0.0% of statements in consensus/istanbul/backend/backendtest
coverage:  24.3% of statements in consensus/istanbul/backend/internal/replica
coverage:  61.2% of statements in consensus/istanbul/core
coverage:  50.0% of statements in consensus/istanbul/db
coverage:   0.0% of statements in consensus/istanbul/proxy
coverage:  64.2% of statements in consensus/istanbul/uptime
coverage:  51.8% of statements in consensus/istanbul/validator
coverage:  79.2% of statements in consensus/istanbul/validator/random

[github-actions[bot]]

[codecov[bot]]

Codecov Report

Attention: 23 lines in your changes are missing coverage. Please review.

Comparison is base (69dbdae) 55.10% compared to head (9bfde3e) 55.08%. Report is 1 commits behind head on master.

Files	Patch %	Lines
eth/api_backend.go	0.00%	8 Missing :warning:
les/api_backend.go	0.00%	8 Missing :warning:
core/types/celo_additions.go	0.00%	5 Missing :warning:
contracts/currency/currency.go	0.00%	2 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #2230 +/- ## ========================================== - Coverage 55.10% 55.08% -0.03% ========================================== Files 683 680 -3 Lines 114538 113847 -691 ========================================== - Hits 63121 62707 -414 + Misses 47528 47293 -235 + Partials 3889 3847 -42 ```

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[piersy]

@hbandura this failure TestEthersJSCompatibility: e2e_test is fixed by my pr #2229 , not sure about the other two failures though

[piersy]

@hbandura this failure TestEthersJSCompatibility: e2e_test is fixed by my pr #2229 , not sure about the other two failures though

Hey @hbandura I started looking into those other failing tests, because they were failing for me and it seems that they are also failing for similar reasons to TestEthersJSCompatibility basically a lack of gingerbread fields on the genesis block. I'm working on a PR to fix all these gingerbread genesis issues and once that is done it should solve your problems here.

[piersy]

@hbandura #2245 has been merged and I think will fix all the flaky tests you are encountering on this PR!