replace use of lazy_static_include_bytes in tests with std::fs::read

[abhijeetbhagat]

Replace use of lazy_static_include_bytes in tests with std::fs::read

Since we don’t need to include test data files in test binaries,
prefer reading the files via std::fs::read rather than using
lazy_static_include_bytes. In release builds the latter results in
the file being read at compilation which is a waste of time.

Fixes: #6665

[mina86]

I’m afraid we may need to take CARGO_MANIFEST_DIR into consideration.
This works when run over cargo test (because cargo test will change
to the manifest directory before executing the test) but when the test
is run directly it fails:

$ ./target/debug/deps/nearcore-92e4a7e0c6bc4d0d -- test_config_from_file

running 1 test
test config::test_config_from_file ... FAILED

failures:

---- config::test_config_from_file stdout ----
thread 'config::test_config_from_file' panicked at 'called `Result::unwrap()` on an `Err` value: Os { code: 2, kind: NotFound, message: "No such file or directory" }', nearcore/src/config.rs:1496:73
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

This doesn’t happen with the previous code.

std::path::Path::new(env!("CARGO_MANIFEST_DIR")).join("...")

should solve that issue.

By the way, could you also take a look at Cargo.toml files and remove
lazy-static-include dependencies which this change makes unnecessary.