H2: Don't show stack trace when failing to build BloomFilter

Only show the exception message.

Change-Id: I210ed24e5baaf4f7b6f62f10f5c0fa448e9079d8

gerrit-cache-h2/src/main/java/com/google/gerrit/server/cache/h2/H2CacheImpl.java

diff --git a/gerrit-cache-h2/src/main/java/com/google/gerrit/server/cache/h2/H2CacheImpl.java b/gerrit-cache-h2/src/main/java/com/google/gerrit/server/cache/h2/H2CacheImpl.java
index 1aaebf5..123bb9a 100644
--- a/gerrit-cache-h2/src/main/java/com/google/gerrit/server/cache/h2/H2CacheImpl.java
+++ b/gerrit-cache-h2/src/main/java/com/google/gerrit/server/cache/h2/H2CacheImpl.java
@@ -388,7 +388,7 @@
           return b;
         }
       } catch (SQLException e) {
-        log.warn("Cannot build BloomFilter for " + url, e);
+        log.warn("Cannot build BloomFilter for " + url + ": " + e.getMessage());
         c = close(c);
         return null;
       } finally {