lean_compiler: avoid duplicate compile-and-run output

[latifkasuli]

Summary

• remove the redundant summary print from try_compile_and_run
• keep compile_and_run as the single printing wrapper
• add a regression test proving try_compile_and_run returns the summary without writing it to stdout

Root cause

try_compile_and_run printed result.metadata.display() and returned a freshly computed display string. compile_and_run then printed the returned string again, so callers of compile_and_run saw the same execution summary twice.

Validation

• cargo fmt --check
• cargo test -p lean_compiler
• cargo clippy -p lean_compiler --all-targets -- -D warnings