Bump max heap size for local canton runs (#1075)

Fixes DACH-NY/cn-test-failures#3885
(Integration test participant `OutOfMemory encountered: Java heap space`)

I didn't touch the initial heap size for now; we only reach it rarely so seems to be more economical this way.

Signed-off-by: Martin Florian <martin.florian@digitalasset.com>

Author: martinflorian-da

start-canton.sh

@@ -188,7 +188,7 @@ tmux new-session -d -s "${tmux_session}"
 
 # Numbers chosen such that we don't run out of memory and CI runs are not measurably slower.
 # Feel free to bump if you encounter issues but make sure the nodes don't run out of memory.
-JAVA_TOOL_OPTIONS="-Xms6g -Xmx6g -Dlogback.configurationFile=./scripts/canton-logback.xml"
+JAVA_TOOL_OPTIONS="-Xms6g -Xmx8g -Dlogback.configurationFile=./scripts/canton-logback.xml"
 
 config_overrides=""
 config_overrides_simtime=""