Cherry-pick: node: relax websocket connection header check (#21646)

[jcortejoso]

Description

Cherry-picking from go-ethereum this PR.
The fix from the PR is needed for Kong and the GCP LB to be able to redirect the websocket properly.

Tested

Tested in baklava forno env with and without Kong as proxy:

╰─ wscat -c wss://baklava-forno-k8s.celo-testnet.org/ws
Connected (press CTRL+C to quit)
> {"jsonrpc":"2.0","method":"eth_blockNumber","params":[],"id":1}
< {"jsonrpc":"2.0","id":1,"result":"0x768513"}

╰─ geth attach wss://baklava-forno-k8s.celo-testnet.org/ws
Welcome to the Geth JavaScript console!

instance: celo/v1.4.0-unstable/linux-amd64/go1.16.8
at block: 7767331 (Wed Sep 22 2021 10:01:28 GMT+0200 (CEST))
 modules: eth:1.0 net:1.0 rpc:1.0 web3:1.0

To exit, press ctrl-d
>

Related issues

• Fixes Websocket connectivity not working as expected  #1683

Backwards compatibility

This celo-monorepo PR needs to be merged/used to deploy new celo-blockchain versions to Forno due to this issue (this endpoint change is already on master).

[piersy]

Coverage from tests in ./e2e_test/... for ./consensus/istanbul/... at commit 5c52d42

coverage:  39.6% of statements across all listed packages
coverage:  50.1% of statements in consensus/istanbul
coverage:  38.0% of statements in consensus/istanbul/backend
coverage:   0.0% of statements in consensus/istanbul/backend/backendtest
coverage:  43.3% of statements in consensus/istanbul/backend/internal/db
coverage:  24.1% of statements in consensus/istanbul/backend/internal/enodes
coverage:  22.6% of statements in consensus/istanbul/backend/internal/replica
coverage:  58.4% of statements in consensus/istanbul/core
coverage:   0.0% of statements in consensus/istanbul/proxy
coverage:  58.1% of statements in consensus/istanbul/uptime
coverage: 100.0% of statements in consensus/istanbul/uptime/store
coverage:  46.1% of statements in consensus/istanbul/validator
coverage:  79.2% of statements in consensus/istanbul/validator/random

[codecov]

Codecov Report

Merging #1698 (5c52d42) into master (46dac57) will decrease coverage by 0.00%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1698      +/-   ##
==========================================
- Coverage   56.09%   56.08%   -0.01%     
==========================================
  Files         606      606              
  Lines       80269    80269              
==========================================
- Hits        45030    45022       -8     
- Misses      31703    31717      +14     
+ Partials     3536     3530       -6     

Impacted Files	Coverage Δ
node/rpcstack.go	83.69% <100.00%> (ø)
p2p/discover/v4_udp.go	76.11% <0.00%> (-4.23%)	⬇️
miner/block.go	48.79% <0.00%> (-2.41%)	⬇️
les/serverpool.go	88.78% <0.00%> (-1.87%)	⬇️
miner/worker.go	56.56% <0.00%> (-1.52%)	⬇️
trie/proof.go	75.28% <0.00%> (-1.50%)	⬇️
p2p/simulations/http.go	70.10% <0.00%> (-0.55%)	⬇️
p2p/discover/v5_udp.go	72.85% <0.00%> (-0.47%)	⬇️
p2p/server.go	65.97% <0.00%> (-0.33%)	⬇️
eth/downloader/downloader.go	76.77% <0.00%> (+0.28%)	⬆️
... and 10 more

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[gastonponti]

LGTM