Database schema mismatch on web_hooks causing 500 error on Add project hook API endpoint

Summary

Attempting to use Add project hook API endpoint when specifying only required attributes results in 500 error which logs show as ActiveRecord::NotNullViolation. Works fine on a different GitLab instance.

Steps to reproduce

1. Have a GitLab version that has done a lot of upgrades over the years
2. Try to create project hook using API endpoint and only id and url attributes

Example Project

Not possible

What is the current bug behavior?

500 error

What is the expected correct behavior?

No 500 error

Relevant logs and/or screenshots

==> /var/log/gitlab/postgresql/current <==
2019-08-01_22:43:40.64618 ERROR:  null value in column "push_events" violates not-null constraint
2019-08-01_22:43:40.64622 DETAIL:  Failing row contains (2953, 19678, 2019-08-01 22:43:40.64372+00, 2019-08-01 22:43:40.64372+00, ProjectHook, null, null, t, null, null, f, t, f, f, f, f, f, null, null, null, null, xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx=
2019-08-01_22:43:40.64622       , xxxxxxxxxxxxxx
2019-08-01_22:43:40.64623       ).
2019-08-01_22:43:40.64623 STATEMENT:  INSERT INTO "web_hooks" ("project_id", "created_at", "updated_at", "issues_events", "encrypted_url", "encrypted_url_iv") VALUES (19678, '2019-08-01 22:43:40.643720', '2019-08-01 22:43:40.643720', 't', 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx=
2019-08-01_22:43:40.64624       ', 'xxxxxxxxxxxxxx
2019-08-01_22:43:40.64625       ') RETURNING "id"

ActiveRecord::NotNullViolation (PG::NotNullViolation: ERROR:  null value in column "push_events" violates not-null constraint
DETAIL:  Failing row contains (2953, 19678, 2019-08-01 22:43:40.64372+00, 2019-08-01 22:43:40.64372+00, ProjectHook, null, null, t, null, null, f, t, f, f, f, f, f, null, null, null, null, xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx=
, xxxxxxxxxxxxxx
).
: INSERT INTO "web_hooks" ("project_id", "created_at", "updated_at", "issues_events", "encrypted_url", "encrypted_url_iv") VALUES (19678, '2019-08-01 22:43:40.643720', '2019-08-01 22:43:40.643720', 't', 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx=
', 'xxxxxxxxxxxxxx
') RETURNING "id"):

Output of checks

Results of GitLab environment info

Expand for output related to GitLab environment info

System information
System:
Current User:   git
Using RVM:      no
Ruby Version:   2.5.3p105
Gem Version:    2.7.9
Bundler Version:1.17.3
Rake Version:   12.3.2
Redis Version:  3.2.12
Git Version:    2.21.0
Sidekiq Version:5.2.7
Go Version:     unknown
GitLab information
Version:        11.11.5
Revision:       b85e6215a85
Directory:      /opt/gitlab/embedded/service/gitlab-rails
DB Adapter:     PostgreSQL
DB Version:     9.6.11
URL:            https://xxxxxxx.com
HTTP Clone URL: https://xxxxxxx.com/some-group/some-project.git
SSH Clone URL:  git@xxxxxxx.com:some-group/some-project.git
Using LDAP:     no
Using Omniauth: yes
Omniauth Providers: saml
GitLab Shell
Version:        9.1.0
Repository storage paths:
- default:      /app/gitlab/git-data/repositories
GitLab Shell path:              /opt/gitlab/embedded/service/gitlab-shell
Git:            /opt/gitlab/embedded/bin/git

Results of GitLab application Check

Expand for output related to the GitLab application check

all passing

Possible fixes

Related to https://gitlab.com/gitlab-org/gitlab-ce/issues/51438