Scenario "Using a persistent Electrum configuration" is fragile

The step “I create a new bitcoin wallet” fails quite often with mainly two errors:

Step: I create a new bitcoin wallet
  Defined at: features/step_definitions/electrum.rb:17
  Used in:    Scenario: Using a persistent Electrum configuration
              features/electrum.feature:2
  Error trace:
    FindFailed: can not find ElectrumEncryptWallet.png on the screen.
    Line ?, in File ? (RuntimeError)
    features/electrum.feature:23:in `When I create a new bitcoin wallet'

Step: I create a new bitcoin wallet
  Defined at: features/step_definitions/electrum.rb:17
  Used in:    Scenario: Using a persistent Electrum configuration
              features/electrum.feature:2
  Error trace:
    FindFailed: can not find ElectrumConnectServer.png on the screen.
    Line ?, in File ? (RuntimeError)
    features/electrum.feature:23:in `When I create a new bitcoin wallet'

Parent Task: #10288

Related issues

Blocked by #9713 (closed)

Original created by @bertagaz on 10475 (Redmine)

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