[WEB-8990] Migrate guarddog and supply_chain_firewall dashboard logos off imgix (DataDog#23605)

* Migrate guarddog and supply_chain_firewall dashboard logos off imgix

Replace datadog-securitylabs.imgix.net logo URLs with canonical DRUID
paths on static.datadoghq.com as part of the Imgix CDN migration (WEB-8990).

* add dark_theme

Author: nsollecito

guarddog/assets/dashboards/guarddog_rules_overview.json

@@ -6,8 +6,8 @@
             "id": 5827532687075026,
             "definition": {
                 "type": "image",
-                "url": "https://datadog-securitylabs.imgix.net/img/guarddog-2-0-release/logo.png?auto=format",
-                "url_dark_theme": "https://datadog-securitylabs.imgix.net/img/guarddog-2-0-release/logo.png?auto=format",
+                "url": "https://static.datadoghq.com/static/images/logos/guarddog_large.svg",
+                "url_dark_theme": "https://static.datadoghq.com/static/images/logos/guarddog_reversed_large.svg",
                 "sizing": "contain",
                 "has_background": false,
                 "has_border": false,

guarddog/assets/dashboards/guarddog_scan_and_ecosystem_overview.json

@@ -6,8 +6,8 @@
             "id": 2918516675459237,
             "definition": {
                 "type": "image",
-                "url": "https://datadog-securitylabs.imgix.net/img/guarddog-2-0-release/logo.png?auto=format",
-                "url_dark_theme": "https://datadog-securitylabs.imgix.net/img/guarddog-2-0-release/logo.png?auto=format",
+                "url": "https://static.datadoghq.com/static/images/logos/guarddog_large.svg",
+                "url_dark_theme": "https://static.datadoghq.com/static/images/logos/guarddog_reversed_large.svg",
                 "sizing": "contain",
                 "has_background": false,
                 "has_border": false,

supply_chain_firewall/assets/dashboards/supply_chain_firewall_events.json

@@ -6,8 +6,8 @@
             "id": 3929729493655156,
             "definition": {
                 "type": "image",
-                "url": "https://datadog-securitylabs.imgix.net/img/introducing-supply-chain-firewall/logo.png",
-                "url_dark_theme": "https://datadog-securitylabs.imgix.net/img/introducing-supply-chain-firewall/logo.png",
+                "url": "https://static.datadoghq.com/static/images/logos/supply-chain-firewall_large.svg",
+                "url_dark_theme": "https://static.datadoghq.com/static/images/logos/supply-chain-firewall_reversed_large.svg",
                 "sizing": "contain",
                 "has_background": false,
                 "has_border": false,