Use more correct changelog entries for refactoring Generator usage (#17890)

Use more correct changelog entries for refactoring `Generator` usage

 - https://github.com/element-hq/synapse/pull/17813
 - https://github.com/element-hq/synapse/pull/17814
 - https://github.com/element-hq/synapse/pull/17815
 - https://github.com/element-hq/synapse/pull/17816
 - https://github.com/element-hq/synapse/pull/17817

### Pull Request Checklist

<!-- Please read
https://element-hq.github.io/synapse/latest/development/contributing_guide.html
before submitting your pull request -->

* [x] Pull request is based on the develop branch
* [x] Pull request includes a [changelog
file](https://element-hq.github.io/synapse/latest/development/contributing_guide.html#changelog).
The entry should:
- Be a short description of your change which makes sense to users.
"Fixed a bug that prevented receiving messages from other servers."
instead of "Moved X method from `EventStore` to `EventWorkerStore`.".
  - Use markdown where necessary, mostly for `code blocks`.
  - End with either a period (.) or an exclamation mark (!).
  - Start with a capital letter.
- Feel free to credit yourself, by adding a sentence "Contributed by
@github_username." or "Contributed by [Your Name]." to the end of the
entry.
* [x] [Code
style](https://element-hq.github.io/synapse/latest/code_style.html) is
correct
(run the
[linters](https://element-hq.github.io/synapse/latest/development/contributing_guide.html#run-the-linters))

changelog.d/17813.bugfix

@@ -1 +0,0 @@
-Avoid lost data on some database query retries.

changelog.d/17813.misc

@@ -0,0 +1 @@
+Refactor database calls to remove `Generator` usage.

changelog.d/17814.bugfix

@@ -1 +0,0 @@
-Avoid lost data on some database query retries.

changelog.d/17814.misc

@@ -0,0 +1 @@
+Refactor database calls to remove `Generator` usage.

changelog.d/17815.bugfix

@@ -1 +0,0 @@
-Avoid lost data on some database query retries.

changelog.d/17815.misc

@@ -0,0 +1 @@
+Refactor database calls to remove `Generator` usage.

changelog.d/17816.bugfix

@@ -1 +0,0 @@
-Avoid lost data on some database query retries.

changelog.d/17816.misc

@@ -0,0 +1 @@
+Refactor database calls to remove `Generator` usage.

changelog.d/17817.bugfix

@@ -1 +0,0 @@
-Avoid lost data on some database query retries.

changelog.d/17817.misc

@@ -0,0 +1 @@
+Refactor database calls to remove `Generator` usage.

changelog.d/17818.bugfix

@@ -1 +0,0 @@
-Avoid lost data on some database query retries.

changelog.d/17818.misc

@@ -0,0 +1 @@
+Refactor database calls to remove `Generator` usage.

changelog.d/17890.misc

@@ -0,0 +1 @@
+Refactor database calls to remove `Generator` usage.