Update line height for prologue headers

[irfano]

Description

This updates the line height of headers on the login prologue screens, as requested from: pffQ75-10m-p2#comment-1027

I set the new line height to 29, which is 1.2 times the text size, as suggested here. I didn't make this change for for all headers since it falls outside the scope of this PR.

Steps to reproduce

Clean install

The tests that have been performed

Screens below

Images/gif

Before	After

• I have considered if this change warrants release notes and have added them to RELEASE-NOTES.txt if necessary. Use the "[Internal]" label for non-user-facing changes.

Reviewer (or Author, in the case of optional code reviews):

Please make sure these conditions are met before approving the PR, or request changes if the PR needs improvement:

• The PR is small and has a clear, single focus, or a valid explanation is provided in the description. If needed, please request to split it into smaller PRs.
• Ensure Adequate Unit Test Coverage: The changes are reasonably covered by unit tests or an explanation is provided in the PR description.
• Manual Testing: The author listed all the tests they ran, including smoke tests when needed (e.g., for refactorings). The reviewer confirmed that the PR works as expected on big (tablet) and small (phone) in case of UI changes, and no regressions are added.

[wpmobilebot]

📲 You can test the changes from this Pull Request in WooCommerce-Wear Android by scanning the QR code below to install the corresponding build.

	App Name	WooCommerce-Wear Android
	Platform	⌚️ Wear OS
	Flavor	Jalapeno
	Build Type	Debug
	Commit	c30a7a7
	Direct Download	woocommerce-wear-prototype-build-pr13420-c30a7a7.apk

[wpmobilebot]

📲 You can test the changes from this Pull Request in WooCommerce Android by scanning the QR code below to install the corresponding build.

	App Name	WooCommerce Android
	Platform	📱 Mobile
	Flavor	Jalapeno
	Build Type	Debug
	Commit	c30a7a7
	Direct Download	woocommerce-prototype-build-pr13420-c30a7a7.apk

[JorgeMucientes]

LGTM!