inconsistent comments in `bindinfo/handle.go`

[Defined2014]

Bug Report

tidb/bindinfo/handle.go

Lines 135 to 136 in 3994bb6

	// No need to acquire the session context lock for ExecRestrictedStmt, it
	// uses another background session.

change ExecRestrictedStmt -> ExecRestrictedSQL

[Defined2014]

/severity minor

[Defined2014]

fixed by #32223