Fix file_name column size in H2AccountPatchReviewStore

file_name store the path to the file within the repository. Absolute file path on
Linux have a maximum of 4096 characters so increase file_name column size to 4096.

This fixes only apply to installations that did not yet migrate to 2.13,
for existing ones, a manual db migration is required.

Manual migration can be done by using H2 web console, Gerrit must be
stopped before otherwise H2 console will not be able to connect to database:
java -jar /path/to/h2.jar -url jdbc:h2:path/to/review_site/db/account_patch_reviews

then execute the following statement:
ALTER TABLE account_patch_reviews ALTER COLUMN file_name VARCHAR(4096) DEFAULT '' NOT NULL

Depending on the number or rows, this statement can take long time, for
example, one million row can take up to 1 minute.

Change-Id: I83ab98acb1581c2a7f6c65a9c2159873421f39ea
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/schema/H2AccountPatchReviewStore.java b/gerrit-server/src/main/java/com/google/gerrit/server/schema/H2AccountPatchReviewStore.java
index b5862f2..6dbe916 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/schema/H2AccountPatchReviewStore.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/schema/H2AccountPatchReviewStore.java
@@ -143,7 +143,7 @@
             + "account_id INTEGER DEFAULT 0 NOT NULL, "
             + "change_id INTEGER DEFAULT 0 NOT NULL, "
             + "patch_set_id INTEGER DEFAULT 0 NOT NULL, "
-            + "file_name VARCHAR(255) DEFAULT '' NOT NULL, "
+            + "file_name VARCHAR(4096) DEFAULT '' NOT NULL, "
             + "CONSTRAINT primary_key_account_patch_reviews "
             + "PRIMARY KEY (account_id, change_id, patch_set_id, file_name)"
             + ")");