Rename `get_e2e_device_keys` to better reflect its purpose (#8205)

... and to show that it does something slightly different to
`_get_e2e_device_keys_txn`.

`include_all_devices` and `include_deleted_devices` were never used (and
`include_deleted_devices` was broken, since that would cause `None`s in the
result which were not handled in the loop below.

Add some typing too.

1 files changed, 1 insertions, 0 deletions

diff --git a/changelog.d/8205.misc b/changelog.d/8205.misc
new file mode 100644
index 0000000000..fb8fd83278
--- /dev/null
+++ b/changelog.d/8205.misc
@@ -0,0 +1 @@
+ Refactor queries for device keys and cross-signatures.