Replace hardcoded ~/go/bin/seid path with seid in scripts

[yzhanginwa]

Describe your changes and provide context

The "/go/bin/seid" is used in the 2 files scripts/benchmark.sh and scripts/initialize_local_chain.sh. It caused problem
for uses whose GOBIN is not the default "/go/bin". For example, I'm a mise user, my local GOBIN is like "~/.local/share/mise/installs/go/1.25.6/bin/go". It's still better to respect the $PATH instead of using hard coded path.

Testing performed to validate your change

I tested both scripts benchmark.sh and initialize_local_chain.sh successfully.

[github-actions]

We truly appreciate your contribution and the time you’ve invested in this PR.
Before we can merge it, we’d love your help addressing the remaining feedback or sharing your perspective.
If we don’t hear back within 2 day(s), this PR will close automatically — but don’t worry, you can reopen it anytime when you’re ready to continue.