fix: template: enforce bounds of template max_ttl (#3662)

This PR makes the following changes:

- enforces lower and upper limits on template `max_ttl_ms`
- adds a migration to enforce 7-day cap on `max_ttl`
- allows setting template `max_ttl` to 0
- updates template edit CLI help to be clearer

coderd/workspaces.go

@@ -32,8 +32,6 @@ import (
 	"github.com/coder/coder/codersdk"
 )
 
-const workspaceDefaultTTL = 12 * time.Hour
-
 var (
 	ttlMin = time.Minute //nolint:revive // min here means 'minimum' not 'minutes'
 	ttlMax = 7 * 24 * time.Hour
@@ -312,11 +310,6 @@ func (api *API) postWorkspacesByOrganization(rw http.ResponseWriter, r *http.Req
 		return
 	}
 
-	if !dbTTL.Valid {
-		// Default to min(12 hours, template maximum). Just defaulting to template maximum can be surprising.
-		dbTTL = sql.NullInt64{Valid: true, Int64: min(template.MaxTtl, int64(workspaceDefaultTTL))}
-	}
-
 	workspace, err := api.Database.GetWorkspaceByOwnerIDAndName(r.Context(), database.GetWorkspaceByOwnerIDAndNameParams{
 		OwnerID: apiKey.UserID,
 		Name:    createWorkspace.Name,
@@ -923,7 +916,8 @@ func validWorkspaceTTLMillis(millis *int64, max time.Duration) (sql.NullInt64, e
 		return sql.NullInt64{}, errTTLMax
 	}
 
-	if truncated > max {
+	// template level
+	if max > 0 && truncated > max {
 		return sql.NullInt64{}, xerrors.Errorf("time until shutdown must be below template maximum %s", max.String())
 	}
 
@@ -1050,10 +1044,3 @@ func splitQueryParameterByDelimiter(query string, delimiter rune, maintainQuotes
 
 	return parts
 }
-
-func min(x, y int64) int64 {
-	if x < y {
-		return x
-	}
-	return y
-}