refactor: extract magic number to constant and improve workflow docs

- Extract 2-second sleep to postgresStabilizationPeriod constant for better maintainability
- Update architecture description to include all accepted values (x86/amd64, arm/arm64)

Author: moizpgedge

.github/workflows/test_images.yaml

@@ -16,7 +16,7 @@ on:
         type: string
         required: true
       architectures:
-        description: "Comma-separated list of architectures to test (x86,arm)"
+        description: "Comma-separated list of architectures to test (x86/amd64, arm/arm64)"
         type: string
         default: "x86,arm"
         required: false

tests/main.go

@@ -15,6 +15,13 @@ import (
 	"github.com/docker/docker/pkg/stdcopy"
 )
 
+const (
+	// postgresStabilizationPeriod is the duration to wait after PostgreSQL
+	// passes readiness checks to allow background workers, extensions, and
+	// internal caches to fully initialize before running tests.
+	postgresStabilizationPeriod = 2 * time.Second
+)
+
 // Test represents a single test case
 type Test struct {
 	Name           string
@@ -419,10 +426,10 @@ func (r *TestRunner) waitForPostgres(timeout time.Duration) error {
 			if err == nil && exitCode == 0 {
 				// Give PostgreSQL a short grace period even after a successful readiness check.
 				// Although pg_isready and a trivial SELECT can succeed, background workers,
-				// extensions, and internal caches may still be initializing. Waiting a fixed
-				// 2 seconds helps ensure a stable database state and reduces test flakiness
-				// in subsequent operations that depend on a fully-initialized instance.
-				time.Sleep(2 * time.Second)
+				// extensions, and internal caches may still be initializing. This delay helps
+				// ensure a stable database state and reduces test flakiness in subsequent
+				// operations that depend on a fully-initialized instance.
+				time.Sleep(postgresStabilizationPeriod)
 				return nil
 			}
 		}