fix/remove duplicated property in PMM strategy

[takuya29]

Before submitting this PR, please make sure:

• Your code builds clean without any errors or warnings
• You are using approved title ("feat/", "fix/", "docs/", "refactor/")

A description of the changes proposed in the pull request:
I found that property and setter of filled_order_delay are doubly defined in pure_market_making.pyx.

Tests performed by the developer:

Tips for QA testing:

[phbrgnomo]

Hello @29Takuya

The Hummingbot Foundation just started the governance process for the community to approve or reject Pull Requests through Pull Request Proposals.

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[takuya29]

Hi @phbrgnomo,

Thank you for letting me know about the new governance process!

I confirmed that three out of four points are satisfied:

• Your Pull Request is targeted to the development branch
• Your branch is up to date with the current development branch
• All GitHub checks have passed
• There is no merging conflicts

It seems that GitHub checks don't run on this PR since I am a first-time contributor.
Could you approve this?

[phbrgnomo]

Since this was your first PR, i hade to manually start the tests. Check back later to see if all of them passed.

[takuya29]

Thank you! I confirmed that all checks have passed.

[RobHBOT]

@29Takuya Takuya did you create a PRP or I can create one for you

[takuya29]

@RobHBOT Sorry, not yet. Could you create it on my behalf?

[JeremyKono]

Hi @29Takuya, are you still willing to work on this PR?

[takuya29]

Hi @JeremyKono, I am willing to work on this.
The latest development branch still has the same issue.

Would it be possible for you to share what I need to merge this PR?

[cardosofede]

@29Takuya this are the new contribution guidelines https://hummingbot.org/developers/contributions/
Please rebase the code to the current development branch and I will review it.

[takuya29]

@cardosofede Thank you for your help!
I rebased with the latest development branch.

[cardosofede]

LGTM

[nikspz]

Need to update with latest dev branch changes and good to go

[nikspz]

Filled order delay not affected, need to update with latest dev branch and good to go

[takuya29]

@cardosofede @nikspz Thank you for your reviews! I updated this PR with the latest dev branch.

[nikspz]

Filled order delay not affected
LGTM

[nikspz]

In behalf of Foundation team we merged this PR to development for the upcoming Hummingbot version 1.12.0