allow repo access by default on dotcom (#63367)

Sourcegraph.com only has public repos, so it is safe to allow access to
all repositories by all users.

This now-deleted code was originally added in
https://github.com/sourcegraph/sourcegraph/pull/26345 to support private
repositories on dotcom. We do not currently support private repositories
on dotcom anymore, and when we do add back that feature, we can figure
out how best to do it and will benefit from fewer special-cases for
dotcom.

## Test plan

CI

Author: sqs

internal/authz/register.go

@@ -3,7 +3,6 @@ package authz
 import (
 	"sync"
 
-	"github.com/sourcegraph/sourcegraph/internal/dotcom"
 	"github.com/sourcegraph/sourcegraph/internal/testutil"
 )
 
@@ -35,12 +34,6 @@ func SetProviders(authzAllowByDefault bool, z []Provider) {
 	authzProviders = z
 	allowAccessByDefault = authzAllowByDefault
 
-	// 🚨 SECURITY: We do not want to allow access by default by any means on
-	// dotcom.
-	if dotcom.SourcegraphDotComMode() {
-		allowAccessByDefault = false
-	}
-
 	authzProvidersReadyOnce.Do(func() {
 		close(authzProvidersReady)
 	})