Restrict syntax for setting ink! e2e test node to auto

[davidsemakula]

Summary

Closes #_

• [n] y/n | Does it introduce breaking changes?
• [n] y/n | Is it dependant on the specific version of cargo-contract or pallet-contracts?

Description

• Currently, both #[ink_e2e::test(backend(node))] and #[ink_e2e::test(backend(node(auto)))] are valid syntax for setting the e2e test node to auto, this PR removes the latter syntax.
• This PR doesn't affect/change the syntax for setting an already running node (i.e. #[ink_e2e::test(backend(node(url = ..)))])

See also #2143 for a similar change

Checklist before requesting a review

• My code follows the style guidelines of this project
• I have added an entry to CHANGELOG.md
• I have commented my code, particularly in hard-to-understand areas
• I have added tests that prove my fix is effective or that my feature works
• Any dependent changes have been merged and published in downstream modules

[github-actions]

🦑 📈 ink! Example Contracts ‒ Changes Report 📉 🦑

These are the results when building the integration-tests/* contracts from this branch with cargo-contract and comparing them to ink! master:

Contract	Upstream Size (kB)	PR Size (kB)	Diff (kB)	Diff (%)	Change
call-builder-return-value	9.249	9.249	0	0	➖
call-runtime	2.071	2.071	0	0	➖
combined-extension	2.149	2.132	-0.017	-0.791066	📉
conditional-compilation	1.502	1.502	0	0	➖
contract-storage	7.58	7.58	0	0	➖
contract-terminate	1.369	1.369	0	0	➖
contract-transfer	1.731	1.731	0	0	➖
cross-contract-calls	7.732	7.732	0	0	➖
cross-contract-calls/other-contract	1.595	1.595	0	0	➖
custom-allocator	7.787	7.787	0	0	➖
custom-environment	2.158	2.158	0	0	➖
dns	7.355	7.355	0	0	➖
e2e-call-runtime	1.32	1.32	0	0	➖
e2e-runtime-only-backend	1.901	1.901	0	0	➖
erc1155	14.345	14.345	0	0	➖
erc20	6.955	6.955	0	0	➖
erc721	10.044	10.044	0	0	➖
events	5.27	5.27	0	0	➖
flipper	1.651	1.651	0	0	➖
incrementer	1.516	1.516	0	0	➖
lang-err-integration-tests/call-builder-delegate	2.65	2.65	0	0	➖
lang-err-integration-tests/call-builder	5.571	5.571	0	0	➖
lang-err-integration-tests/constructors-return-value	1.997	1.997	0	0	➖
lang-err-integration-tests/contract-ref	5.062	5.062	0	0	➖
lang-err-integration-tests/integration-flipper	1.827	1.827	0	0	➖
lazyvec-integration-test	4.66	4.66	0	0	➖
mapping-integration-tests	8.036	8.036	0	0	➖
mother	12.753	12.753	0	0	➖
multi-contract-caller	6.654	6.654	0	0	➖
multi-contract-caller/accumulator	1.388	1.388	0	0	➖
multi-contract-caller/adder	1.922	1.922	0	0	➖
multi-contract-caller/subber	1.942	1.942	0	0	➖
multisig	21.871	21.871	0	0	➖
payment-channel	5.742	5.742	0	0	➖
psp22-extension	7.083	7.083	0	0	➖
rand-extension	2.977	2.977	0	0	➖
sr25519-verification	1.154	1.154	0	0	➖
static-buffer	2.578	2.578	0	0	➖
trait-dyn-cross-contract-calls	2.899	2.899	0	0	➖
trait-dyn-cross-contract-calls/contracts/incrementer	1.557	1.557	0	0	➖
trait-erc20	7.331	7.331	0	0	➖
trait-flipper	1.502	1.502	0	0	➖
trait-incrementer	1.626	1.626	0	0	➖
upgradeable-contracts/delegator	3.96	3.96	0	0	➖
upgradeable-contracts/delegator/delegatee	1.641	1.641	0	0	➖
upgradeable-contracts/delegator/delegatee2	1.641	1.641	0	0	➖
upgradeable-contracts/set-code-hash-migration	1.755	1.755	0	0	➖
upgradeable-contracts/set-code-hash-migration/migration	1.462	1.462	0	0	➖
upgradeable-contracts/set-code-hash-migration/updated-incrementer	1.909	1.909	0	0	➖
upgradeable-contracts/set-code-hash	1.755	1.755	0	0	➖
upgradeable-contracts/set-code-hash/updated-incrementer	1.733	1.733	0	0	➖
wildcard-selector	2.858	2.858	0	0	➖

Link to the run | Last update: Mon Mar 11 10:15:23 CET 2024

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 53.72%. Comparing base (c14d00d) to head (a6997c6).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2146      +/-   ##
==========================================
- Coverage   53.76%   53.72%   -0.05%     
==========================================
  Files         224      224              
  Lines        7084     7084              
  Branches     3129     3129              
==========================================
- Hits         3809     3806       -3     
- Misses       3275     3278       +3     

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[cmichi]

@davidsemakula Can you make sure this is reflected in the 5.x part of ink-docs?