Add a stress test profile (#6901)

# Objective
This adds a custom profile for testing against stress tests. Bevy seemingly gets notably faster with LTO turned on. To more accurately depict production level performance, LTO and other rustc-level optimizations should be enabled when performance testing on stress tests.

Also updated the stress test docs to reflect that users should be using it.

Cargo.toml

@@ -1608,3 +1608,8 @@ inherits = "release"
 opt-level = "z"
 lto = "fat"
 codegen-units = 1
+
+[profile.stress-test]
+inherits = "release"
+lto = "fat"
+panic = "abort"

examples/stress_tests/README.md

@@ -1,3 +1,12 @@
 # Stress tests
 
-These examples are used to stress test Bevy's performance in various ways. These should be run with the --release argument to cargo or equivalent optimization, otherwise they will be very slow.
+These examples are used to stress test Bevy's performance in various ways. These
+should be run with the "stress-test" profile to accurately represent performance
+in production, otherwise they will run in cargo's default "dev" profile which is
+very slow.
+
+## Example Command
+
+```bash
+cargo run --profile stress-test --example <EXAMPLE>
+```