chore: Adjust CODEOWNERS to point at matrix team

Author: jason-famedly

.github/CODEOWNERS

@@ -1,8 +1,2 @@
 # Automatically request reviews from the synapse-core and dendrite-core teams when a pull request comes in.
-* @matrix-org/synapse-core @matrix-org/dendrite-core
-
-# For modifications to complement internals, also directly request review from Kegan.
-/build/ @matrix-org/synapse-core @matrix-org/dendrite-core @kegsay
-/cmd/ @matrix-org/synapse-core @matrix-org/dendrite-core @kegsay
-/internal/ @matrix-org/synapse-core @matrix-org/dendrite-core @kegsay
-/runtime/ @matrix-org/synapse-core @matrix-org/dendrite-core @kegsay
+* @famedly/matrix-team