Fix #5267: Not able to navigate back from story.

[Vishwajith-Shettigar]

Explanation

Fixes #5267
Destroyed ExplorationActivity before creating TopicActivity to prevent loop between the same two activity, when user tries to go back.

Essential Checklist

• The PR title and explanation each start with "Fix #bugnum: " (If this PR fixes part of an issue, prefix the title with "Fix part of #bugnum: ...".)
• Any changes to scripts/assets files have their rationale included in the PR explanation.
• The PR follows the style guide.
• The PR does not contain any unnecessary code changes from Android Studio (reference).
• The PR is made from a branch that's not called "develop" and is up-to-date with "develop".
• The PR is assigned to the appropriate reviewers (reference).

For UI-specific PRs only

Before

no_way_home.webm

After

home_coming.webm

If your PR includes UI-related changes, then:

• Add screenshots for portrait/landscape for both a tablet & phone of the before & after UI changes
• For the screenshots above, include both English and pseudo-localized (RTL) screenshots (see RTL guide)
• Add a video showing the full UX flow with a screen reader enabled (see accessibility guide)
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• Add a screenshot demonstrating that you ran affected Espresso tests locally & that they're passing

[Vishwajith-Shettigar]

Hi @adhiamboperes, based on my testing, I haven't encountered any regression errors. Please take a low-level pass.
Thank you.

[oppiabot]

Hi @Vishwajith-Shettigar, I'm going to mark this PR as stale because it hasn't had any updates for 7 days. If no further activity occurs within 7 days, it will be automatically closed so that others can take up the issue.
If you are still working on this PR, please make a follow-up commit within 3 days (and submit it for review, if applicable). Please also let us know if you are stuck so we can help you!

[oppiabot]

Hi @Vishwajith-Shettigar, I'm going to mark this PR as stale because it hasn't had any updates for 7 days. If no further activity occurs within 7 days, it will be automatically closed so that others can take up the issue.
If you are still working on this PR, please make a follow-up commit within 3 days (and submit it for review, if applicable). Please also let us know if you are stuck so we can help you!

[oppiabot]

Hi @Vishwajith-Shettigar, I'm going to mark this PR as stale because it hasn't had any updates for 7 days. If no further activity occurs within 7 days, it will be automatically closed so that others can take up the issue.
If you are still working on this PR, please make a follow-up commit within 3 days (and submit it for review, if applicable). Please also let us know if you are stuck so we can help you!

[oppiabot]

Hi @Vishwajith-Shettigar, I'm going to mark this PR as stale because it hasn't had any updates for 7 days. If no further activity occurs within 7 days, it will be automatically closed so that others can take up the issue.
If you are still working on this PR, please make a follow-up commit within 3 days (and submit it for review, if applicable). Please also let us know if you are stuck so we can help you!

[oppiabot]

Hi @Vishwajith-Shettigar, I'm going to mark this PR as stale because it hasn't had any updates for 7 days. If no further activity occurs within 7 days, it will be automatically closed so that others can take up the issue.
If you are still working on this PR, please make a follow-up commit within 3 days (and submit it for review, if applicable). Please also let us know if you are stuck so we can help you!

[oppiabot]

Hi @Vishwajith-Shettigar, I'm going to mark this PR as stale because it hasn't had any updates for 7 days. If no further activity occurs within 7 days, it will be automatically closed so that others can take up the issue.
If you are still working on this PR, please make a follow-up commit within 3 days (and submit it for review, if applicable). Please also let us know if you are stuck so we can help you!

[adhiamboperes]

Thanks @Vishwajith-Shettigar!

Please see my comment in-line.

[Vishwajith-Shettigar]

@adhiamboperes, PTAL.

[adhiamboperes]

LGTM, Thanks @Vishwajith-Shettigar!

[oppiabot]

Unassigning @adhiamboperes since they have already approved the PR.

[oppiabot]

Hi @Vishwajith-Shettigar, this PR is ready to be merged. Please address any remaining comments prior to merging, and feel free to ask someone to merge your PR once the CI checks pass and you're happy with it. Thanks!