Associate a name with database connections

This helps when working out which connection to the database is doing what.

tests/branch-updated-emails.scm

@@ -107,6 +107,7 @@ Summary of changes:
 (test-begin "test-branch-updated-emails")
 
 (with-postgresql-connection
+ "test-branch-updated-emails"
  (lambda (conn)
    (test-assert "enqueue-job-for-email works"
      (with-postgresql-transaction

tests/jobs-load-new-guix-revision.scm

@@ -12,6 +12,7 @@
 (test-begin "jobs-load-new-guix-revision")
 
 (with-postgresql-connection
+ "test-jobs-load-new-guix-revision"
  (lambda (conn)
    (test-equal "select-job-for-commit works"
      '()

tests/model-derivation.scm

@@ -6,6 +6,7 @@
 (test-begin "test-model-derivation")
 
 (with-postgresql-connection
+ "test-model-derivation"
  (lambda (conn)
    (test-equal "valid-systems"
      '()

tests/model-git-branch.scm

@@ -8,6 +8,7 @@
 (test-begin "test-model-git-branch")
 
 (with-postgresql-connection
+ "test-module-git-branch"
  (lambda (conn)
    (test-assert "insert-git-branch-entry works"
      (with-postgresql-transaction

tests/model-git-repository.scm

@@ -6,6 +6,7 @@
 (test-begin "test-model-git-repository")
 
 (with-postgresql-connection
+ "test-model-git-repository"
  (lambda (conn)
    (test-assert "returns an id for a non existent URL"
      (with-postgresql-transaction

tests/model-license-set.scm

@@ -25,6 +25,7 @@
         "https://example.com/why-license-2")))))
 
  (with-postgresql-connection
+  "test-model-license-set"
   (lambda (conn)
     (with-postgresql-transaction
      conn

tests/model-license.scm

@@ -23,6 +23,7 @@
         "https://example.com/why-license-2")))))
 
  (with-postgresql-connection
+  "test-model-license"
   (lambda (conn)
     (with-postgresql-transaction
      conn

tests/model-package-metadata.scm

@@ -37,6 +37,7 @@
                 (guix-data-service model package-metadata))
 
    (with-postgresql-connection
+    "test-model-package-metadata"
     (lambda (conn)
       (test-assert "inferior-packages->package-metadata-ids"
         (with-postgresql-transaction