fix(bdd): resolve server address and credentials only from env

[chengxilo]

Which issue does this PR address?

Closes #3883

Rationale

A fallback turns a configuration bug into either a misleading connection error
or, worse, a green run against the wrong server. Tests should be loud when they
are broken.

What changed?

Each suite now reads those values through a required-env helper that aborts when
a variable is unset or empty, and the image no longer carries defaults. The PHP
path moves onto the key names the other seven SDKs already use
(IGGY_TCP_ADDRESS, IGGY_ROOT_USERNAME, IGGY_ROOT_PASSWORD); the PHP SDK
suite keeps its own defaults, so only the names change there. Two CI steps run
bdd/go outside run-bdd-tests.sh and were relying on the removed defaults,
one of them with no environment block at all; both now pass the variables
explicitly.

Local Execution

• Passed
• Pre-commit hooks ran

AI Usage

1. Claude (Claude Code).
2. Implementation
3. I reviewed the code line by line. There was some changes to PHP unit test by AI but I reverted them. I am not planning to make the unit test be affected by this change since they don't have ./scripts/run-bdd-tests.sh to handle the chores. It's kinda annoying to export some environment variable everytime you want to run the unit tests.
4. Yes

[github-actions]

Thanks for the PR. It is labeled S-waiting-on-review and queued for review.

Slash commands (own line, regular comment) move it around the queue:

• /ready - back to S-waiting-on-review after addressing feedback
• /author - flip to S-waiting-on-author while you finish changes
• /request-review @user-or-team - request a reviewer

See CONTRIBUTING.md for details.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 20.23%. Comparing base (cc269ef) to head (84d74a6).

Additional details and impacted files

@@              Coverage Diff              @@
##             master    #3935       +/-   ##
=============================================
- Coverage     83.85%   20.23%   -63.63%     
  Complexity     1358     1358               
=============================================
  Files          1212     1211        -1     
  Lines        166843   138120    -28723     
  Branches     134304   105708    -28596     
=============================================
- Hits         139905    27947   -111958     
- Misses        23298   109498    +86200     
+ Partials       3640      675     -2965     

Components	Coverage Δ
Rust Core	0.21% <ø> (-84.41%)	⬇️
Java SDK	66.67% <ø> (ø)
C# SDK	74.99% <ø> (-1.54%)	⬇️
Python SDK	90.13% <ø> (ø)
PHP SDK	84.48% <ø> (ø)
Node SDK	95.94% <ø> (+0.09%)	⬆️
Go SDK	68.32% <ø> (-0.05%)	⬇️
see 677 files with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[slbotbm]

foreign/node/README.md:124-151 still tells users that IGGY_TCP_ADDRESS is the only BDD configuration variable and shows npm run test:bdd without any environment variables. Update this README to direct users to scripts/run-bdd-tests.sh node, matching foreign/node/src/bdd/README.md.

[chengxilo]

tks! I updated the README.md, it should be ok now.