We don't use all of the Stack functionality for it, so drop useless methods
and avoid some interface conversions. It increases single-node TPS by about
0.9%, so nothing really important there, but not a bad change either. Maybe it
can be reworked again with generics though.
Problem: failing part of TestLoad:
```
=== RUN TestLoad/loadgo,_check_signers
cli_test.go:160:
Error Trace: /home/circleci/go/src/github.com/nspcc-dev/neo-go/cli/vm/cli_test.go:160
/home/circleci/go/src/github.com/nspcc-dev/neo-go/cli/vm/cli_test.go:147
/home/circleci/go/src/github.com/nspcc-dev/neo-go/cli/vm/cli_test.go:444
Error: command took too long time
Test: TestLoad/loadgo,_check_signers
```
Solution: split the test into multiple parts to reduce test execution time.
If VUB-th block is received, we still can't guaranty that transaction
wasn't accepted to chain. Back this situation by rolling back to a
poll-based waiter.
Do not block subscribers until the unsubscription request to RPC server
is completed. Otherwise, another notification may be received from the
RPC server which will block the unsubscription process.
At the same time, fix event-based waiter. We must not block the receiver
channel during unsubscription because there's a chance that subsequent
event will be sent by the server. We need to read this event in order not
to block the WSClient's readloop.
Bad contract -> no contract. Unfortunately we've got a broken
6f1837723768f27a6f6a14452977e3e0e264f2cc contract on the mainnet which can't
be decoded (even though it had been saved successfully), so this is a
temporary fix for #2801 to be able to start mainnet node after shutdown.
v.estack is used throughout the code to work with estack, while ctx.sc.estack
is (theoretically) just a reference to it that is saved on script load and
restored to v.estack on context unload. The problem is that v.estack can grow
as we use it and can be reallocated away from its original slice (saved in the
ctx.sc.estack), so either ctx.sc.estack should be a pointer or we need to
ensure that it's correct when loading a new script. The second approach is a
bit safer for now and it fixes#2798.
And fix failing test along the way:
```
2022-11-11T12:37:47.0413934Z === RUN TestResetDB
2022-11-11T12:37:47.0414557Z 2022-11-11T12:36:54.510Z INFO initial gas supply is not set or wrong, setting default value {"InitialGASSupply": "52000000"}
2022-11-11T12:37:47.0415288Z 2022-11-11T12:36:54.510Z INFO MaxBlockSize is not set or wrong, setting default value {"MaxBlockSize": 262144}
2022-11-11T12:37:47.0416020Z 2022-11-11T12:36:54.510Z INFO MaxBlockSystemFee is not set or wrong, setting default value {"MaxBlockSystemFee": 900000000000}
2022-11-11T12:37:47.0416786Z 2022-11-11T12:36:54.510Z INFO MaxTransactionsPerBlock is not set or wrong, using default value {"MaxTransactionsPerBlock": 512}
2022-11-11T12:37:47.0417725Z 2022-11-11T12:36:54.510Z INFO MaxValidUntilBlockIncrement is not set or wrong, using default value {"MaxValidUntilBlockIncrement": 5760}
2022-11-11T12:37:47.0418415Z 2022-11-11T12:36:54.510Z INFO Hardforks are not set, using default value
2022-11-11T12:37:47.0419272Z 2022-11-11T12:36:54.523Z INFO no storage version found! creating genesis block
2022-11-11T12:37:47.0419997Z 2022-11-11T12:36:54.529Z INFO chain is already at the proper state {"height": 0}
2022-11-11T12:37:47.0420974Z testing.go:1097: TempDir RemoveAll cleanup: remove C:\Users\RUNNER~1\AppData\Local\Temp\TestResetDB671187463\001\chains\privnet\000001.log: The process cannot access the file because it is being used by another process.
2022-11-11T12:37:47.0421606Z --- FAIL: TestResetDB (1.99s)
```
