refactor: remove obsolete // +build tag (#2774)

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## Overview

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From Go 1.17, the preferred syntax for build constraints is
`//go:build`,
which replaces the old `// +build` form. The old style is now considered
deprecated but still supported for backward compatibility.

This change removes the obsolete `// +build xxx` line, keeping only the
modern `//go:build xxx` directive.

More info: golang/go#41184 and
https://go.dev/doc/go1.17#build-lines

Design Doc / Proposal：
https://go.dev/design/draft-gobuild

Signed-off-by: wyrapeseed <[email protected]>

Author: wyrapeseed

scripts/run-evm-nodes.go

@@ -1,5 +1,4 @@
 //go:build run_evm
-// +build run_evm
 
 package main
 

scripts/run.go

@@ -1,5 +1,4 @@
 //go:build run
-// +build run
 
 package main
 

scripts/test_cover.go

@@ -1,5 +1,4 @@
 //go:build cover
-// +build cover
 
 package main
 

scripts/tidy.go

@@ -1,5 +1,4 @@
 //go:build tidy
-// +build tidy
 
 package main