Review PR `default_accounts()`

[arturoBeccar]

Review the PR on default_accounts()
use-ink/ink#1955

In particular, review these failing tests:

integration-tests/call-runtime/Cargo.toml 

integration-tests/erc20/Cargo.toml 

integration-tests/erc721/Cargo.toml 

integration-tests/multisig/Cargo.toml 

integration-tests/trait-erc20/Cargo.toml

[XianPaz]

All tests are running