fix: small fix and refactor after testing EkuboV2 (#188)

* fix: add `balance_owner` attribute for ekubo_v2 components

* refactor: rename `ekubo` into `ekubo-v2`

* refactor: freeze `substreams-helper` version in ekubo V2 module

* docs: improve integration test comment

* docs: add TODO to remove `balance_owner` in favor of `AccountBalances`

---------

Co-authored-by: zizou <111426680+flopell@users.noreply.github.com>

substreams/ethereum-ekubo-v2/buf.gen.yaml

@@ -0,0 +1,12 @@
+
+version: v1
+plugins:
+- plugin: buf.build/community/neoeinstein-prost:v0.2.2
+  out: src/pb
+  opt:
+    - file_descriptor_set=false
+
+- plugin: buf.build/community/neoeinstein-prost-crate:v0.3.1
+  out: src/pb
+  opt:
+    - no_features